Labarin wani ɓangare ne na batun binciken "Fasahohin bioremediation na ci gaba da hanyoyin sake amfani da sinadarai na halitta (SOC)". Duba duk labarai 14
Ana amfani da ƙananan ƙwayoyin hydrocarbons masu ɗauke da sinadarin polycyclic aromatic hydrocarbons (PAHs) kamar naphthalene da naphthalenes da aka maye gurbinsu (methylnaphthalene, naphthoic acid, 1-naphthyl-N-methylcarbamate, da sauransu) sosai a masana'antu daban-daban kuma suna da guba ga halittu, suna haifar da maye gurbi da/ko kuma suna haifar da cutar kansa ga halittu. Waɗannan mahaɗan halitta na roba (SOCs) ko xenobiotics ana ɗaukar su a matsayin gurɓatattun abubuwa masu mahimmanci kuma suna haifar da babbar barazana ga muhallin duniya da lafiyar jama'a. Ƙarfin ayyukan ɗan adam (misali gas na kwal, tace mai, hayakin ababen hawa da aikace-aikacen noma) yana ƙayyade yawansu, ƙaddara da jigilar waɗannan mahaɗan da ke ko'ina da kuma masu dorewa. Baya ga hanyoyin magani/cirewa na zahiri da sinadarai, fasahar kore da mara muhalli kamar bioremediation, waɗanda ke amfani da ƙananan ƙwayoyin cuta waɗanda ke iya lalata POCs gaba ɗaya ko canza su zuwa samfuran da ba su da guba, sun fito a matsayin madadin aminci, mai araha kuma mai kyau. Nau'o'in ƙwayoyin cuta daban-daban da ke cikin phyla Proteobacteria (Pseudomonas, Pseudomonas, Comamonas, Burkholderia, da Neosphingobacterium), Firmicutes (Bacillus da Paenibacillus), da Actinobacteria (Rhodococcus da Arthrobacter) a cikin ƙwayoyin cuta na ƙasa sun nuna ikon lalata mahaɗan halitta daban-daban. Nazarin metabolism, genomics, da nazarin metagenomic suna taimaka mana mu fahimci sarkakiyar catabolic da bambancin da ke cikin waɗannan nau'ikan rayuwa masu sauƙi, waɗanda za a iya amfani da su don ingantaccen lalata biogradation. Rayuwar PAHs na dogon lokaci ya haifar da fitowar sabbin nau'ikan lalacewa ta hanyar canja wurin kwayoyin halitta ta kwance ta amfani da abubuwan kwayoyin halitta kamar plasmids, transposons, bacteriophages, tsibiran genomic, da abubuwan haɗin gwiwa. Ilimin halittu na tsarin da injiniyan kwayoyin halitta na takamaiman keɓancewa ko al'ummomin samfura (consortia) na iya ba da damar cikakken, sauri da ingantaccen gyaran waɗannan PAHs ta hanyar tasirin haɗin gwiwa. A cikin wannan bita, mun mayar da hankali kan hanyoyin rayuwa daban-daban da bambancinsu, tsarin kwayoyin halitta da bambancinsu, da kuma martanin ƙwayoyin halitta/daidaitawa na naphthalene da ƙwayoyin cuta masu lalata naphthalene da aka maye gurbinsu. Wannan zai samar da bayanai game da muhalli don amfani da filin da inganta nau'in don ingantaccen maganin biorediation.
Saurin ci gaban masana'antu (masana'antar mai, noma, magunguna, rini na yadi, kayan kwalliya, da sauransu) ya ba da gudummawa ga ci gaban tattalin arzikin duniya da inganta yanayin rayuwa. Wannan ci gaban da aka samu ya haifar da samar da adadi mai yawa na mahaɗan halitta (SOCs), waɗanda ake amfani da su don ƙera kayayyaki daban-daban. Waɗannan mahaɗan ƙasashen waje ko SOCs sun haɗa da polycyclic aromatic hydrocarbons (PAHs), magungunan kashe kwari, magungunan kashe kwari, masu yin filastik, rini, magunguna, organophosphates, masu hana harshen wuta, masu narkewar sinadarai masu canzawa, da sauransu. Ana fitar da su cikin yanayi, yanayin halittu na ruwa da na ƙasa inda suke da tasirin girma dabam-dabam, suna haifar da mummunan tasiri ga nau'ikan halittu daban-daban ta hanyar canza halayen sinadarai da tsarin al'umma (Petrie et al., 2015; Bernhardt et al., 2017; Sarkar et al., 2020). Gurɓatattun abubuwa da yawa masu ƙamshi suna da tasiri mai ƙarfi da ɓarna a kan halittu da yawa da ba su da matsala/wuraren da ke cike da halittu masu rai (misali murjani, kankara a Arctic/Antarctic, tafkuna masu tsayi, laka mai zurfi a cikin teku, da sauransu) (Jones 2010; Beyer et al. 2020; Nordborg et al. 2020). Nazarin ilimin ƙasa na baya-bayan nan ya nuna cewa adana abubuwa masu rai na roba (misali gurɓatattun abubuwa masu ƙamshi) da abubuwan da suka samo asali a saman gine-ginen wucin gadi (muhalli da aka gina) (misali wuraren tarihi na al'adu da abubuwan tarihi da aka yi da dutse, dutse, itace da ƙarfe) yana hanzarta lalacewarsu (Gadd 2017; Liu et al. 2018). Ayyukan ɗan adam na iya ƙaruwa da ta'azzara lalacewar halittu na abubuwan tarihi da gine-gine ta hanyar gurɓatar iska da sauyin yanayi (Liu et al. 2020). Waɗannan gurɓatattun abubuwa na halitta suna amsawa da tururin ruwa a cikin yanayi kuma suna zama akan tsarin, suna haifar da lalacewar zahiri da sinadarai na kayan. An san cewa lalacewar halittu a matsayin canje-canje marasa kyau a cikin bayyanar da halayen kayan da halittu masu rai ke haifarwa waɗanda ke shafar kiyaye su (Pochon da Jaton, 1967). Ƙarin aikin ƙwayoyin cuta (metabolism) na waɗannan mahaɗan na iya rage ingancin tsarin, ingancin kiyayewa da ƙimar al'adu (Gadd, 2017; Liu et al., 2018). A gefe guda kuma, a wasu lokuta, an gano cewa daidaitawa da amsawar ƙwayoyin cuta ga waɗannan gine-gine suna da amfani yayin da suke samar da biofilms da sauran ɓawon kariya waɗanda ke rage yawan ruɓewa/rushewa (Martino, 2016). Saboda haka, haɓaka ingantattun dabarun kiyayewa mai ɗorewa na dogon lokaci don abubuwan tarihi na dutse, ƙarfe da itace yana buƙatar fahimtar mahimman hanyoyin da ke cikin wannan tsari. Idan aka kwatanta da hanyoyin halitta (tsarin ƙasa, gobarar daji, fashewar aman wuta, halayen tsirrai da ƙwayoyin cuta), ayyukan ɗan adam suna haifar da sakin manyan adadin polycyclic aromatic hydrocarbons (PAHs) da sauran carbon na halitta (OC) cikin yanayin halittu. Yawancin PAHs da ake amfani da su a aikin gona (magungunan kashe kwari da magungunan kashe kwari kamar DDT, atrazine, carbaryl, pentachlorophenol, da sauransu), masana'antu (danyen mai, laka/sharar mai, robobi da aka samo daga man fetur, PCBs, masu tacewa, sabulun wanki, masu kashe kwari, masu feshi, turare da abubuwan kiyayewa), kayayyakin kulawa na sirri (maganin rana, masu kashe kwari, masu kashe kwari da musks na polycyclic) da kuma harsasai (masu fashewa kamar 2,4,6-TNT) su ne masu yuwuwar xenobiotics waɗanda za su iya yin tasiri ga lafiyar duniya (Srogi, 2007; Vamsee-Krishna da Phale, 2008; Petrie et al., 2015). Ana iya faɗaɗa wannan jerin don haɗawa da mahaɗan da aka samo daga man fetur (man fetur, man shafawa, asfaltenes), bioplastics masu nauyin ƙwayoyin halitta, da ruwa mai ionic (Amde et al., 2015). Tebur 1 ya lissafa gurɓatattun abubuwa daban-daban da aikace-aikacensu a masana'antu daban-daban. A cikin 'yan shekarun nan, hayakin da ke haifar da gurɓataccen sinadarai masu canzawa a cikin ɗan adam, da kuma iskar carbon dioxide da sauran iskar gas mai gurbata muhalli, sun fara ƙaruwa (Dvorak et al., 2017). Duk da haka, tasirin da ke haifar da ɗan adam ya fi na halitta yawa. Bugu da ƙari, mun gano cewa wasu SOCs sun ci gaba da wanzuwa a cikin mahalli da yawa na muhalli kuma an gano su a matsayin gurɓatattun abubuwa masu tasowa waɗanda ke da mummunan tasiri ga halittu (Hoto na 1). Hukumomin muhalli kamar Hukumar Kare Muhalli ta Amurka (USEPA) sun haɗa da yawancin waɗannan gurɓatattun abubuwa a cikin jerin abubuwan da suka fi fifiko saboda halayensu na cytotoxic, genotoxic, mutagenic, da carcinogenic. Saboda haka, ana buƙatar ƙa'idodi masu tsauri na zubar da shara da dabarun da suka dace don magance sharar gida/cire ta daga gurɓatattun halittu. Hanyoyi daban-daban na magani na zahiri da na sinadarai kamar pyrolysis, maganin zafi na oxidative, iskar iska, cika ƙasa, ƙonawa, da sauransu ba su da tasiri kuma suna da tsada kuma suna haifar da lalata, guba kuma suna da wahalar magancewa daga samfuran. Tare da ƙaruwar wayar da kan jama'a game da muhalli a duniya, ƙananan halittu masu iya lalata waɗannan gurɓatattun abubuwa da abubuwan da suka samo asali (kamar halogenated, nitro, alkyl da/ko methyl) suna jan hankalin jama'a sosai (Fennell et al., 2004; Haritash da Kaushik, 2009; Phale et al., 2020; Sarkar et al., 2020; Schwanemann et al., 2020). Amfani da waɗannan ƙananan halittu masu neman mafaka na asali kaɗai ko a cikin al'adu daban-daban (mazauna) don kawar da gurɓatattun abubuwa masu ƙamshi yana da fa'idodi dangane da amincin muhalli, farashi, inganci, inganci, da dorewa. Masu bincike kuma suna binciken haɗa hanyoyin ƙwayoyin cuta tare da hanyoyin redox na lantarki, wato tsarin bioelectrochemical (BES), a matsayin fasaha mai kyau don magance/cire gurɓatattun abubuwa (Huang et al., 2011). Fasahar BES ta jawo hankali sosai saboda ingancinta, ƙarancin farashi, amincin muhalli, aikin zafin ɗaki, kayan da suka dace da halittu, da kuma ikon dawo da kayayyaki masu mahimmanci (misali, wutar lantarki, mai, da sinadarai) (Pant et al., 2012; Nazari et al., 2020). Zuwan jerin kwayoyin halitta masu inganci da kayan aiki/hanyoyin omics ya samar da wadataccen sabbin bayanai game da tsarin kwayoyin halitta, proteomics, da fluxomics na halayen ƙwayoyin cuta daban-daban masu lalata. Haɗa waɗannan kayan aikin da ilimin halittu na tsarin ya ƙara haɓaka fahimtarmu game da zaɓi da daidaita hanyoyin catabolic da aka yi niyya a cikin ƙwayoyin cuta (watau, ƙirar metabolism) don cimma ingantaccen lalata biogradation mai inganci. Don tsara dabarun bioremediation masu tasiri ta amfani da ƙananan ƙwayoyin cuta masu dacewa, muna buƙatar fahimtar yuwuwar biochemical, bambancin metabolism, tsarin kwayoyin halitta, da ilimin halittu (autoecology/synecology) na ƙananan ƙwayoyin cuta.
Hoto na 1. Tushe da hanyoyin PAHs masu ƙarancin ƙwayoyin halitta ta hanyar muhalli daban-daban da kuma abubuwa daban-daban da ke shafar biota. Layuka masu lanƙwasa suna wakiltar hulɗa tsakanin abubuwan da ke tattare da yanayin halittu.
A cikin wannan bita, mun yi ƙoƙarin taƙaita bayanai kan lalacewar PAHs masu sauƙi kamar naphthalene da maye gurbin naphthalenes ta hanyar ƙwayoyin cuta daban-daban waɗanda ke rufe hanyoyin rayuwa da bambancin rayuwa, enzymes da ke da hannu a cikin lalacewar ƙwayoyin halitta, tsarin kwayoyin halitta/abun da ke ciki da bambancin halitta, martanin ƙwayoyin halitta da fannoni daban-daban na gyaran ƙwayoyin halitta. Fahimtar matakan biochemical da kwayoyin halitta zai taimaka wajen gano nau'ikan masu masaukin baki masu dacewa da ƙarin injiniyancin kwayoyin halitta don ingantaccen gyaran ƙwayoyin halitta na irin waɗannan gurɓatattun abubuwa masu mahimmanci. Wannan zai taimaka wajen haɓaka dabarun kafa consortia na ƙwayoyin cuta na musamman a wurin don ingantaccen gyaran ƙwayoyin halitta.
Kasancewar adadi mai yawa na sinadarai masu guba da haɗari (wanda ke gamsar da ƙa'idar Huckel 4n + 2π electrons, n = 1, 2, 3, ...) yana haifar da babbar barazana ga hanyoyin sadarwa na muhalli daban-daban kamar iska, ƙasa, laka, da saman ƙasa da ruwan ƙasa (Puglisi et al., 2007). Waɗannan sinadarai suna da zoben benzene guda ɗaya (monocyclic) ko zoben benzene da yawa (polycyclic) waɗanda aka shirya a layi, kusurwa ko tsari kuma suna nuna kwanciyar hankali (kwanciyar hankali/rashin kwanciyar hankali) a cikin muhalli saboda yawan kuzarin amsawa mara kyau da rashin ƙarfi (rashin ƙarfi), wanda za'a iya bayyana shi ta hanyar rashin son ruwa da yanayin da ya ragu. Idan aka ƙara maye gurbin zoben aromatic da methyl (-CH3), carboxyl (-COOH), hydroxyl (-OH), ko sulfonate (-HSO3), yana ƙara zama mai karko, yana da ƙarfi ga macromolecules, kuma yana da tarin halittu a cikin tsarin halittu (Seo et al., 2009; Phale et al., 2020). An haɗa wasu ƙananan ƙwayoyin hydrocarbons masu ƙarancin nauyin ƙwayoyin halitta (LMWAHs), kamar naphthalene da abubuwan da suka samo asali [methylnaphthalene, naphthoic acid, naphthalenesulfonate, da 1-naphthyl N-methylcarbamate (carbaryl)], a cikin jerin gurɓatattun halittu masu mahimmanci ta Hukumar Kare Muhalli ta Amurka a matsayin masu guba, masu canza yanayi, da/ko masu haifar da cutar kansa (Cerniglia, 1984). Sakin wannan nau'in NM-PAHs cikin muhalli na iya haifar da tarin waɗannan mahaɗan a dukkan matakan sarkar abinci, wanda hakan ke shafar lafiyar halittun halittu (Binkova et al., 2000; Srogi, 2007; Quinn et al., 2009).
Tushen da hanyoyin da PAHs ke bi zuwa biota galibi suna ta hanyar ƙaura da hulɗa tsakanin sassan halittu daban-daban kamar ƙasa, ruwan ƙasa, ruwan saman, amfanin gona da yanayi (Arey da Atkinson, 2003). Hoto na 1 yana nuna hulɗa da rarraba PAHs masu ƙarancin nauyin ƙwayoyin halitta daban-daban a cikin yanayin halittu da hanyoyinsu zuwa fallasa ga biota/mutane. Ana ajiye PAHs a saman abubuwa sakamakon gurɓatar iska da kuma ta hanyar ƙaura (zubar da hayakin ababen hawa), iskar gas na masana'antu (haɗakar da kwal, konewa da samar da coke) da kuma adana su. Ayyukan masana'antu kamar ƙera yadi na roba, rini da fenti; adana itace; sarrafa roba; ayyukan kera siminti; samar da magungunan kashe kwari; da aikace-aikacen noma sune manyan hanyoyin PAHs a cikin tsarin ƙasa da na ruwa (Bamforth da Singleton, 2005; Wick et al., 2011). Bincike ya nuna cewa ƙasa a yankunan birni da birane, kusa da manyan hanyoyi, da kuma a manyan birane sun fi saurin kamuwa da sinadarin hydrocarbons masu kama da polycyclic aromatic hydrocarbons (PAHs) saboda hayakin da ake fitarwa daga tashoshin wutar lantarki, dumama gidaje, jigilar ababen hawa ta iska da ta hanyoyi, da ayyukan gini (Suman et al., 2016). (2008) sun nuna cewa PAHs a cikin ƙasa kusa da hanyoyi a New Orleans, Louisiana, Amurka sun kai 7189 μg/kg, yayin da a sararin samaniya, sun kai 2404 μg/kg kawai. Hakazalika, an ruwaito cewa matakan PAH har zuwa 300 μg/kg a yankunan da ke kusa da wuraren haƙa kwal a biranen Amurka da dama (Kanaly da Harayama, 2000; Bamforth da Singleton, 2005). An ruwaito cewa ƙasa daga biranen Indiya daban-daban kamar Delhi (Sharma et al., 2008), Agra (Dubey et al., 2014), Mumbai (Kulkarni da Venkataraman, 2000) da Visakhapatnam (Kulkarni et al., 2014) tana ɗauke da yawan PAHs masu yawa. Ana iya haɗa sinadarai masu ƙamshi cikin sauƙi a cikin barbashin ƙasa, abubuwan halitta da ma'adanai na yumbu, don haka suna zama manyan nutsewar carbon a cikin halittu masu rai (Srogi, 2007; Peng et al., 2008). Manyan hanyoyin PAHs a cikin halittu masu rai sune ruwan sama (ruwan sama da busasshe da tururin ruwa), kwararar birane, fitar da ruwan shara, sake cika ruwan ƙasa da sauransu (Srogi, 2007). An kiyasta cewa kusan kashi 80% na PAHs a cikin halittu masu rai na ruwa suna fitowa ne daga ruwan sama, lalata ƙasa, da fitar da shara (Motelay-Massei et al., 2006; Srogi, 2007). Yawan PAHs a cikin ruwan saman ko magudanar ruwa daga wuraren zubar da shara mai ƙarfi daga ƙarshe yana ɓuɓɓuga cikin ruwan ƙasa, wanda ke haifar da babbar barazana ga lafiyar jama'a tunda fiye da kashi 70% na al'ummar Kudu da Kudu maso Gabashin Asiya suna shan ruwan ƙasa (Duttagupta et al., 2019). Wani bincike na baya-bayan nan da Duttagupta et al. (2020) na nazarin koguna (32) da ruwan ƙasa (235) daga Yammacin Bengal, Indiya, ya gano cewa an kiyasta cewa kashi 53% na mazauna birane da kashi 44% na mazauna karkara (jimillar mazauna miliyan 20) na iya fuskantar naphthalene (4.9–10.6 μg/L) da abubuwan da suka samo asali. Bambancin yanayin amfani da ƙasa da ƙaruwar fitar da ruwan ƙasa ana ɗaukar su a matsayin manyan abubuwan da ke daidaita jigilar PAHs masu ƙarancin nauyin kwayoyin halitta a ƙarƙashin ƙasa. An gano cewa kwararar ruwa a fannin noma, fitar da ruwan sharar birni da na masana'antu, da fitar da sharar gida/sharar gida mai ƙarfi suna shafar PAHs a cikin kwaruruka da laka a ƙarƙashin ƙasa. Ruwan sama mai yawa yana ƙara ta'azzara gurɓatar PAH. An ruwaito cewa yawan PAHs da abubuwan da suka samo asali daga alkyl (jimilla 51) sun ragu a koguna/magudanar ruwa a duk duniya, kamar Kogin Fraser, Kogin Louan, Kogin Denso, Kogin Missouri, Kogin Anacostia, Kogin Ebro, da Kogin Delaware (Yunker et al., 2002; Motelay-Massei et al., 2006; Li et al., 2010; Amoako et al., 2011; Kim et al., 2018). A cikin laka na kogin Ganges, an gano cewa naphthalene da phenanthrene sune mafi mahimmanci (an gano su a cikin kashi 70% na samfuran) (Duttagupta et al., 2019). Bugu da ƙari, bincike ya nuna cewa chlorine na ruwan sha na iya haifar da samuwar PAHs masu guba waɗanda ke ɗauke da iskar oxygen da chlorine (Manoli da Samara, 1999). PAHs suna taruwa a cikin hatsi, 'ya'yan itatuwa da kayan lambu sakamakon shan su daga ƙasa mai gurɓata, ruwan ƙasa da ruwan sama (Fismes et al., 2002). Yawancin halittu na ruwa kamar kifi, mussels, clams da jatan lande suna gurɓata da PAHs ta hanyar cin abinci da ruwan teku mai gurɓata, da kuma ta cikin kyallen takarda da fata (Mackay da Fraser, 2000). Hanyoyin girki/sarrafawa kamar gasa, gasawa, shan taba, soya, busarwa, yin burodi da girkin gawayi suma na iya haifar da adadi mai yawa na PAHs a cikin abinci. Wannan ya dogara ne da zaɓin kayan shan taba, abun ciki na phenolic/ƙamshi hydrocarbon, tsarin girki, nau'in hita, abun da ke cikin danshi, wadatar iskar oxygen da zafin ƙonewa (Guillén et al., 2000; Gomes et al., 2013). An kuma gano polycyclic aromatic hydrocarbons (PAHs) a cikin madara a yawan da ya bambanta (0.75–2.1 mg/L) (Girelli et al., 2014). Tarin waɗannan PAHs a cikin abinci ya kuma dogara ne akan halayen sinadaran abinci, yayin da tasirinsu mai guba yana da alaƙa da ayyukan jiki, aikin metabolism, sha, rarrabawa da rarraba jiki (Mechini et al., 2011).
An daɗe da sanin guba da illolin polycyclic aromatic hydrocarbons (PAHs) (Cherniglia, 1984). Ƙananan ƙwayoyin polycyclic aromatic hydrocarbons (LMW-PAHs) (zobba biyu zuwa uku) na iya ɗaurewa da ƙwayoyin macromolecules daban-daban kamar DNA, RNA da sunadarai kuma suna haifar da cutar kansa (Santarelli et al., 2008). Saboda yanayin hydrophobic ɗinsu, membranes ɗin lipids suna raba su. A cikin mutane, cytochrome P450 monooxygenases yana oxidize PAHs zuwa epoxides, wasu daga cikinsu suna da matuƙar amsawa (misali, baediol epoxide) kuma yana iya haifar da canza ƙwayoyin halitta na yau da kullun zuwa waɗanda ke da lahani (Marston et al., 2001). Bugu da ƙari, samfuran canji na PAHs kamar quinones, phenols, epoxides, diols, da sauransu sun fi guba fiye da mahaɗan iyaye. Wasu PAHs da tsaka-tsakin metabolism ɗinsu na iya shafar hormones da enzymes daban-daban a cikin metabolism, ta haka suna yin mummunan tasiri ga ci gaba, tsarin jijiyoyi na tsakiya, tsarin haihuwa da garkuwar jiki (Swetha da Phale, 2005; Vamsee-Krishna et al., 2006; Oostingh et al., 2008). An ruwaito cewa fallasa ga PAHs masu ƙarancin nauyin kwayoyin halitta na ɗan gajeren lokaci yana haifar da lalacewar aikin huhu da thrombosis a cikin masu fama da asma da kuma ƙara haɗarin kamuwa da cutar kansar fata, huhu, mafitsara da ciki (Olsson et al., 2010; Diggs et al., 2011). Nazarin dabbobi ya kuma nuna cewa fallasa PAH na iya yin mummunan tasiri ga aikin haihuwa da ci gaba kuma yana iya haifar da cataracts, lalacewar koda da hanta, da jaundice. An nuna cewa samfuran PAH biotransformation daban-daban kamar diols, epoxides, quinones da free radicals (cations) suna samar da abubuwan DNA. An nuna cewa hanyoyin da ke da ƙarfi suna canza injinan kwafi na DNA, yayin da hanyoyin da ba su da ƙarfi na iya cire DNA (galibi zuwa adenine wani lokacin kuma zuwa guanine); duka biyun na iya haifar da kurakurai da ke haifar da maye gurbi (Schweigert et al. 2001). Bugu da ƙari, quinones (benzo-/pan-) na iya samar da nau'in iskar oxygen mai amsawa (ROS), wanda ke haifar da mummunar illa ga DNA da sauran ƙwayoyin cuta, wanda hakan ke shafar aikin/rayuwa na nama (Ewa da Danuta 2017). An ruwaito cewa yawan fallasa ga ƙarancin yawan pyrene, biphenyl da naphthalene na haifar da ciwon daji a cikin dabbobin gwaji (Diggs et al. 2012). Saboda gubar da ke tattare da su, tsaftacewa/cire waɗannan PAHs daga wuraren da abin ya shafa/guba shine fifiko.
An yi amfani da hanyoyi daban-daban na zahiri da sinadarai don cire PAHs daga wurare/muhalli da suka gurɓata. Tsaruka kamar ƙonawa, cire sinadarin chlorine, iskar shaka ta UV, gyarawa, da cire sinadarin solvent suna da illoli da yawa, ciki har da ƙirƙirar samfuran da suka lalace, sarkakiyar tsari, batutuwan aminci da ƙa'idoji, ƙarancin inganci, da tsadar farashi. Duk da haka, lalata ƙwayoyin cuta (wanda ake kira bioremediation) wata hanya ce mai kyau wacce ta ƙunshi amfani da ƙwayoyin cuta a cikin nau'in al'adu ko yankuna masu tsarki. Idan aka kwatanta da hanyoyin zahiri da na sinadarai, wannan tsari yana da kyau ga muhalli, ba ya cutarwa, yana da inganci, kuma yana da dorewa. Ana iya yin gyaran halittu a wurin da abin ya shafa (a wurin) ko a wurin da aka shirya musamman (ex situ) kuma saboda haka ana ɗaukarsa a matsayin hanyar gyara mai ɗorewa fiye da hanyoyin zahiri da na sinadarai na gargajiya (Juhasz da Naidu, 2000; Andreoni da Gianfreda, 2007; Megharaj et al., 2011; Phale et al., 2020; Sarkar et al., 2020).
Fahimtar matakan da ƙwayoyin cuta ke ɗauka wajen lalata gurɓatattun abubuwa masu ƙamshi yana da matuƙar tasiri ga kimiyya da tattalin arziki ga dorewar muhalli da muhalli. Ana adana kimanin gram 2.1 × 1018 na carbon (C) a cikin laka da mahaɗan halitta (watau mai, iskar gas, da kwal, watau, man fetur) a duk duniya, wanda hakan ke ba da gudummawa mai mahimmanci ga zagayowar carbon ta duniya. Duk da haka, saurin masana'antu, haƙo man fetur, da ayyukan ɗan adam suna lalata waɗannan ma'ajiyar carbon ta lithospheric, suna fitar da kimanin gram 5.5 × 1015 na carbon na halitta (a matsayin gurɓatattun abubuwa) zuwa sararin samaniya kowace shekara (Gonzalez-Gaya et al., 2019). Yawancin wannan carbon na halitta yana shiga cikin yanayin ƙasa da na ruwa ta hanyar lalata ƙasa, jigilar kaya, da kwararar ruwa. Bugu da ƙari, sabbin gurɓatattun abubuwa da aka samo daga man fetur na halitta, kamar robobi, masu daidaita filastik da masu daidaita filastik (phthalates da isomers ɗinsu), suna gurɓata yanayin halittu na ruwa, ƙasa da na ruwa da biota ɗinsu sosai, ta haka suna ƙara haɗarin yanayi a duniya. Nau'o'in microplastics daban-daban, nanoplastics, gutsuttsuran filastik da samfuran monomer masu guba da aka samo daga polyethylene terephthalate (PET) sun taru a Tekun Pacific tsakanin Arewacin Amurka da Kudu maso Gabashin Asiya, suna samar da "Babban Filin Shara na Pacific", suna cutar da rayuwar ruwa (Newell et al., 2020). Nazarin kimiyya ya tabbatar da cewa ba zai yiwu a cire irin waɗannan gurɓatattun abubuwa/sharar ta kowace hanya ta zahiri ko ta sinadarai ba. A cikin wannan mahallin, ƙananan halittu masu amfani su ne waɗanda ke iya sarrafa gurɓatattun abubuwa ta hanyar oxidative zuwa carbon dioxide, makamashin sinadarai da sauran samfuran da ba su da guba waɗanda daga ƙarshe ke shiga wasu hanyoyin zagayowar abinci mai gina jiki (H, O, N, S, P, Fe, da sauransu). Don haka, fahimtar yanayin ƙwayoyin cuta na gurɓataccen ƙamshi da kuma kula da muhalli yana da mahimmanci don tantance zagayowar carbon microbial, kasafin kuɗin carbon da haɗarin yanayi na gaba. Ganin buƙatar gaggawa don cire irin waɗannan mahaɗan daga muhalli, masana'antun muhalli daban-daban da suka mai da hankali kan fasahohin tsabta sun bayyana. A madadin haka, ana ɗaukar kimanta sharar masana'antu/sunadaran sharar gida da aka tara a cikin yanayin halittu (watau tsarin sharar gida zuwa wadata) a matsayin ɗaya daga cikin ginshiƙan tattalin arziki mai zagaye da manufofin ci gaba mai ɗorewa (Close et al., 2012). Saboda haka, fahimtar ɓangarorin metabolism, enzymatic da genetic na waɗannan 'yan takarar da ke iya lalata ƙasa yana da matuƙar mahimmanci don kawar da irin waɗannan gurɓatattun abubuwa masu ƙamshi da kuma gyara su yadda ya kamata.
Daga cikin gurɓatattun abubuwa masu ƙamshi da yawa, muna ba da kulawa ta musamman ga PAHs masu ƙarancin nauyi kamar naphthalene da naphthalenes da aka maye gurbinsu. Waɗannan mahaɗan manyan abubuwan haɗin man fetur ne da aka samo daga man fetur, rini na yadi, kayayyakin amfani, magungunan kashe ƙwari (mothballs da magungunan kashe ƙwari), masu yin filastik da tannins kuma saboda haka suna yaɗuwa a cikin halittu da yawa (Preuss et al., 2003). Rahotanni na baya-bayan nan sun nuna tarin yawan naphthalene a cikin laka na ruwa, ƙasa mai ƙarƙashin ƙasa da ƙasa, yankunan vadose da gadajen kogi, suna nuna yadda yake tara abubuwa a cikin muhalli (Duttagupta et al., 2019, 2020). Tebur na 2 ya taƙaita halayen sinadarai na jiki, aikace-aikace da tasirin lafiya na naphthalene da abubuwan da ya samo asali. Idan aka kwatanta da sauran PAHs masu nauyin ƙwayoyin halitta, naphthalene da abubuwan da ya samo asali ba su da isasshen hydrophobic, suna narkewa cikin ruwa kuma suna yaɗuwa sosai a cikin yanayin halittu, don haka galibi ana amfani da su azaman samfuran abubuwa don nazarin metabolism, kwayoyin halitta da bambancin metabolism na PAHs. Yawancin ƙwayoyin cuta suna iya sarrafa naphthalene da abubuwan da suka samo asali, kuma akwai cikakken bayani game da hanyoyin da suke bi wajen sarrafa su, enzymes da fasalulluka na tsari (Mallick et al., 2011; Phale et al., 2019, 2020). Bugu da ƙari, an sanya naphthalene da abubuwan da suka samo asali a matsayin abubuwan da aka yi amfani da su don tantance gurɓatar muhalli saboda yawansu da kuma samuwarsu. Hukumar Kare Muhalli ta Amurka ta kiyasta cewa matsakaicin matakan naphthalene shine 5.19 μg a kowace mita mai siffar cubic daga hayakin sigari, galibi daga ƙonewa mara cikakke, da kuma 7.8 zuwa 46 μg daga hayakin gefe, yayin da fallasa ga creosote da naphthalene ya ninka sau 100 zuwa 10,000 (Preuss et al. 2003). An gano musamman naphthalene yana da guba ta numfashi ta nau'in, yanki, da jinsi da kuma cutar kansa. Dangane da nazarin dabbobi, Hukumar Bincike Kan Ciwon Daji ta Duniya (IARC) ta rarraba naphthalene a matsayin "mai yuwuwar cutar kansa ta ɗan adam" (Rukunin 2B)1. Fuskantar naphthalenes da aka maye gurbinsu, galibi ta hanyar shaƙa ko kuma shan su ta hanyar baki (baki), yana haifar da raunin ƙwayoyin huhu kuma yana ƙara yawan kamuwa da ciwon daji na huhu a cikin beraye da beraye (Shirin Nazarin Toxicology na Ƙasa na 2). Abubuwan da ke haifar da hakan sun haɗa da tashin zuciya, amai, ciwon ciki, gudawa, ciwon kai, ruɗani, gumi mai yawa, zazzabi, tachycardia, da sauransu. A gefe guda kuma, an ruwaito cewa carbaryl mai maganin kwari mai faɗi (1-naphthyl N-methylcarbamate) yana da guba ga marasa lafiya a cikin ruwa, masu ruwa da tsaki, ƙudan zuma da mutane kuma an nuna cewa yana hana acetylcholinesterase wanda ke haifar da gurgunta (Smulders et al., 2003; Bulen da Distel, 2011). Saboda haka, fahimtar hanyoyin lalata ƙwayoyin cuta, daidaita kwayoyin halitta, halayen enzymatic da ƙwayoyin halitta yana da mahimmanci don haɓaka dabarun bioremediation a cikin muhallin da ya gurɓata.
Tebur na 2. Cikakken bayani game da halayen sinadaran jiki, amfani, hanyoyin ganowa da cututtukan da ke da alaƙa da naphthalene da abubuwan da suka samo asali.
A cikin gurɓatattun wurare, gurɓatattun abubuwa masu ƙamshi na hydrophobic da lipophilic na iya haifar da tasirin ƙwayoyin halitta iri-iri akan ƙwayoyin halitta na muhalli (al'umma), kamar canje-canje a cikin ruwan membrane, permeability na membrane, kumburin lipid bilayer, rushewar canja wurin makamashi (sarkar jigilar lantarki/ƙarfin proton), da kuma ayyukan sunadaran da ke da alaƙa da membrane (Sikkema et al., 1995). Bugu da ƙari, wasu tsaka-tsaki masu narkewa kamar catechols da quinones suna samar da nau'in oxygen mai amsawa (ROS) kuma suna samar da ƙari tare da DNA da sunadarai (Penning et al., 1999). Don haka, yawan irin waɗannan mahaɗan a cikin yanayin halittu yana haifar da matsin lamba na zaɓi ga al'ummomin ƙwayoyin cuta don su zama masu lalata abubuwa masu inganci a matakai daban-daban na ilimin halittar jiki, gami da ɗaukar/sufuri, canjin ƙwayoyin halitta, haɗuwa/amfani, da rarrabawa.
Binciken Ribosomal Database Project-II (RDP-II) ya nuna cewa jimillar nau'ikan ƙwayoyin cuta 926 an ware su daga al'adun da suka shafi ƙwayoyin cuta ko kuma waɗanda suka gurbata da naphthalene ko abubuwan da suka samo asali. Ƙungiyar Proteobacteria tana da mafi yawan wakilai (n = 755), sai Firmicutes (52), Bacteroidetes (43), Actinobacteria (39), Tenericutes (10), da ƙwayoyin cuta marasa rarrabuwa (8) (Hoto na 2). Wakilan γ-Proteobacteria (Pseudomonadales da Xanthomonadales) sun mamaye dukkan ƙungiyoyin Gram-negative tare da babban abun ciki na G+C (54%), yayin da Clostridiales da Bacillales (30%) ƙungiyoyi ne masu ƙarancin abun ciki na G+C. An ruwaito cewa Pseudomonas (mafi yawan nau'ikan, nau'ikan 338) suna iya lalata naphthalene da abubuwan da ke cikinsa na methyl a cikin gurɓatattun halittu daban-daban (kwal, man fetur, ɗanyen mai, laka, ɗigon mai, ruwan shara, sharar halitta da wuraren zubar da shara) da kuma a cikin yanayin halittu marasa lalacewa (ƙasa, koguna, laka da ruwan ƙasa) (Hoto na 2). Bugu da ƙari, nazarin wadatarwa da nazarin metagenomic na wasu daga cikin waɗannan yankuna sun nuna cewa nau'ikan Legionella da Clostridium marasa al'adu na iya samun ƙarfin lalata, wanda ke nuna buƙatar haɓaka waɗannan ƙwayoyin cuta don nazarin sabbin hanyoyi da bambancin rayuwa.
Hoto na 2. Bambancin rarrabuwar kawuna da rarrabawar muhalli na wakilan ƙwayoyin cuta a cikin muhallin da aka gurbata da abubuwan da aka samo daga naphthalene da naphthalene.
Daga cikin nau'ikan ƙwayoyin cuta masu ƙamshi masu lalata hydrocarbon, yawancinsu suna iya lalata naphthalene a matsayin tushen carbon da makamashi kawai. An bayyana jerin abubuwan da ke faruwa a cikin metabolism naphthalene ga Pseudomonas sp. (nau'ikan: NCIB 9816-4, G7, AK-5, PMD-1 da CSV86), Pseudomonas stutzeri AN10, Pseudomonas fluorescens PC20 da sauran nau'ikan (ND6 da AS1) (Mahajan et al., 1994; Resnick et al., 1996; Annweiler et al., 2000; Basu et al., 2003; Dennis da Zylstra, 2004; Sota et al., 2006; Ana fara samar da metabolism ta hanyar dioxygenase mai yawan abubuwa [naphthalene dioxygenase (NDO), wani zobe mai dauke da sinadarin hydroxylating dioxygenase] wanda ke haifar da iskar shaka ta daya daga cikin zoben naphthalene mai kamshi ta amfani da iskar oxygen ta kwayoyin halitta a matsayin wani substrate, yana canza naphthalene zuwa cis-naphthalenediol (Hoto na 3). Ana canza Cis-dihydrodiol zuwa 1,2-dihydroxynaphthalene ta hanyar dehydrogenase. Dioxygenase mai raba zobe, 1,2-dihydroxynaphthalene dioxygenase (12DHNDO), yana canza 1,2-dihydroxynaphthalene zuwa 2-hydroxychromene-2-carboxylic acid. Isomerization na enzymatic cis-trans yana samar da trans-o-hydroxybenzylidenepyruvate, wanda hydratase aldolase ke rabawa zuwa salicylic aldehyde da pyruvate. Pyruvate na acid na halitta shine farkon mahaɗin C3 da aka samo daga kwarangwal naphthalene carbon kuma aka tura shi zuwa tsakiyar hanyar carbon. Bugu da ƙari, salicylaldehyde dehydrogenase wanda ke dogara da NAD+ yana canza salicylaldehyde zuwa salicylic acid. Metabolism a wannan matakin ana kiransa "hanyar sama" ta lalata naphthalene. Wannan hanyar ta zama ruwan dare a yawancin ƙwayoyin cuta masu lalata naphthalene. Duk da haka, akwai wasu keɓancewa kaɗan; misali, a cikin thermophilic Bacillus hamburgii 2, Naphthalene 2,3-dioxygenase ne ke fara lalata naphthalene don samar da 2,3-dihydroxynaphthalene (Annweiler et al., 2000).
Hoto na 3. Hanyoyin naphthalene, methylnaphthalene, naphthoic acid, da kuma lalacewar carbaryl. Lambobin da aka zana suna wakiltar enzymes waɗanda ke da alhakin sauya naphthalene da abubuwan da suka samo asali zuwa samfuran da ke gaba. 1 - naphthalene dioxygenase (NDO); 2, cis-dihydrodiol dehydrogenase; 3, 1,2-dihydroxynaphthalene dioxygenase; 4, 2-hydroxychromene-2-carboxylic acid isomerase; 5, trans-O-hydroxybenzylidenepyruvate hydratase aldolase; 6, salicylaldehyde dehydrogenase; 7, salicylate 1-hydroxylase; 8, catechol 2,3-dioxygenase (C23DO); 9, 2-hydroxymuconate semialdehyde dehydrogenase; 10, 2-oxopent-4-enoate hydratase; 11, 4-hydroxy-2-oxopentanoate aldolase; 12, acetaldehyde dehydrogenase; 13, catechol-1,2-dioxygenase (C12DO); 14, muconate cycloisomerase; 15, muconolactone delta-isomerase; 16, β-ketoadipatenollactone hydrolase; 17, β-ketoadipate succinyl-CoA transferase; 18, β-ketoadipate-CoA thiolase; 19, succinyl-CoA: acetyl-CoA succinyltransferase; 20, salicylate 5-hydroxylase; 21 - gentisate 1,2-dioxygenase (GDO); 22, maleylpyruvate isomerase; 23, fumarylpyruvate hydrolase; 24, methylnaphthalene hydroxylase (NDO); 25, hydroxymethylnaphthalene dehydrogenase; 26, naphthaldehyde dehydrogenase; 27, 3-formylsalicylic acid oxidase; 28, hydroxyisophthalate decarboxylase; 29, carbaryl hydrolase (CH); 30, 1-naphthol-2-hydroxylase.
Dangane da kwayoyin halitta da kuma yanayin kwayoyin halittarsa, ana ƙara samar da salicylic acid ta hanyar hanyar catechol ta amfani da salicylate 1-hydroxylase (S1H) ko kuma ta hanyar hanyar gentisate ta amfani da salicylate 5-hydroxylase (S5H) (Hoto na 3). Tunda salicylic acid shine babban matsakaici a cikin metabolism naphthalene (hanyar sama), matakan daga salicylic acid zuwa tsakiyar TCA galibi ana kiransu da hanyar ƙasa, kuma kwayoyin halittar an tsara su zuwa operon guda ɗaya. Abu ne da aka saba gani cewa kwayoyin halittar da ke cikin hanyar sama operon (nah) da kuma hanyar ƙasa operon (sal) ana tsara su ta hanyar abubuwan da suka shafi tsari; misali, NahR da salicylic acid suna aiki azaman masu haifar da abubuwa, suna ba wa operons biyu damar metabolize naphthalene gaba ɗaya (Phale et al., 2019, 2020).
Bugu da ƙari, ana raba catechol zuwa 2-hydroxymuconate semialdehyde ta hanyar hanyar meta ta hanyar catechol 2,3-dioxygenase (C23DO) (Yen et al., 1988) sannan a ƙara samar da hydrolyze ta hanyar 2-hydroxymuconate semialdehyde hydrolase don samar da 2-hydroxypent-2,4-dienoic acid. Sannan ana canza 2-hydroxypent-2,4-dienoate zuwa pyruvate da acetaldehyde ta hanyar hydratase (2-oxopent-4-enoate hydratase) da aldolase (4-hydroxy-2-oxopentanoate aldolase) sannan a shiga tsakiyar hanyar carbon (Hoto na 3). A madadin haka, ana raba catechol zuwa cis,cis-muconate ta hanyar hanyar ortho ta hanyar catechol 1,2-oxygenase (C12DO). Muconate cycloisomerase, muconolactone isomerase, da β-ketoadipate-nollactone hydrolase suna canza cis,cis-muconate zuwa 3-oxoadipate, wanda ke shiga tsakiyar hanyar carbon ta hanyar succinyl-CoA da acetyl-CoA (Nozaki et al., 1968) (Hoto na 3).
A cikin hanyar gentisate (2,5-dihydroxybenzoate), ana raba zoben aromatic ta hanyar gentisate 1,2-dioxygenase (GDO) don samar da maleylpyruvate. Ana iya haɗa wannan samfurin kai tsaye zuwa pyruvate da malate, ko kuma a haɗa shi don samar da fumarylpyruvate, wanda daga nan za a iya haɗa shi zuwa pyruvate da fumarate (Larkin da Day, 1986). An lura da zaɓin hanyar madadin a cikin ƙwayoyin cuta na Gram-negative da Gram-positive a matakan biochemical da genetic (Morawski et al., 1997; Whyte et al., 1997). Kwayoyin cuta na Gram-negative (Pseudomonas) sun fi son amfani da salicylic acid, wanda shine ke haifar da metabolism naphthalene, yana cire shi zuwa catechol ta amfani da salicylate 1-hydroxylase (Gibson da Subramanian, 1984). A gefe guda kuma, a cikin ƙwayoyin cuta masu ƙwaya (Rhodococcus), salicylate 5-hydroxylase yana canza salicylic acid zuwa gentisic acid, yayin da salicylic acid ba shi da wani tasiri na inductive akan kwafi na kwayoyin halittar naphthalene (Grund et al., 1992) (Hoto na 3).
An ruwaito cewa nau'ikan kamar Pseudomonas CSV86, Oceanobacterium NCE312, Marinhomonas naphthotrophicus, Sphingomonas paucimobilis 2322, Vibrio cyclotrophus, Pseudomonas fluorescens LP6a, Pseudomonas da Mycobacterium na iya lalata monomethylnaphthalene ko dimethylnaphthalene (Dean-Raymond da Bartha, 1975; Cane da Williams, 1982; Mahajan et al., 1994; Dutta et al., 1998; Hedlund et al., 1999). Daga cikinsu, an yi nazari a sarari kan hanyar lalata Pseudomonas sp. CSV86 ta 1-methylnaphthalene da 2-methylnaphthalene a matakan biochemical da enzymatic (Mahajan et al., 1994). 1-Methylnaphthalene ana metabolize shi ta hanyoyi biyu. Da farko, zoben aromatic ana hydroxylated (zoben methylnaphthalene mara maye gurbinsa) don samar da cis-1,2-dihydroxy-1,2-dihydro-8-methylnaphthalene, wanda aka ƙara oxidize zuwa methyl salicylate da methylcatechol, sannan ya shiga tsakiyar hanyar carbon bayan an raba zoben (Hoto na 3). Wannan hanyar ana kiranta "hanyar tushen carbon". A cikin "hanyar detoxification" ta biyu, ƙungiyar methyl za a iya hydroxylated ta NDO don samar da 1-hydroxymethylnaphthalene, wanda aka ƙara oxidize zuwa 1-naphthoic acid kuma a fitar da shi cikin yanayin al'ada azaman samfurin ƙarshe. Nazarin ya nuna cewa nau'in CSV86 ba zai iya girma akan 1- da 2-naphthoic acid a matsayin tushen carbon da makamashi ba, yana tabbatar da hanyar kawar da gubobi (Mahajan et al., 1994; Basu et al., 2003). A cikin 2-methylnaphthalene, ƙungiyar methyl tana shan hydroxylation ta hanyar hydroxylase don samar da 2-hydroxymethylnaphthalene. Bugu da ƙari, zoben da ba a maye gurbinsa ba na zoben naphthalene yana shan hydroxylation na zobe don samar da dihydrodiol, wanda aka haɗa shi da 4-hydroxymethylcatechol a cikin jerin halayen enzyme-catalyzed kuma yana shiga tsakiyar hanyar carbon ta hanyar hanyar raba zobe ta meta-ring. Hakazalika, an ruwaito S. paucimobilis 2322 yana amfani da NDO don hydroxylate 2-methylnaphthalene, wanda aka ƙara yin oxidation don samar da methyl salicylate da methylcatechol (Dutta et al., 1998).
Naphthoic acid (wanda aka maye gurbinsa/wanda ba a maye gurbinsa ba) samfuran detoxification/biotransformation ne da aka samar a lokacin lalacewar methylnaphthalene, phenanthrene da anthracene kuma aka sake su zuwa cikin hanyar al'ada da aka kashe. An ruwaito cewa ƙasa tana ware Stenotrophomonas maltophilia CSV89 tana iya metabolize 1-naphthoic acid a matsayin tushen carbon (Phale et al., 1995). Metabolism yana farawa da dihydroxylation na zoben aromatic don samar da 1,2-dihydroxy-8-carboxynaphthalene. Ana haɗa diol da aka samu zuwa catechol ta hanyar 2-hydroxy-3-carboxybenzylidenepyruvate, 3-formylsalicylic acid, 2-hydroxyisophthalic acid da salicylic acid kuma yana shiga tsakiyar hanyar carbon ta hanyar hanyar raba meta-ring (Hoto na 3).
Carbaryl maganin kashe kwari ne na naphthyl carbamate. Tun bayan juyin juya halin kore a Indiya a shekarun 1970, amfani da takin zamani da magungunan kashe kwari ya haifar da karuwar fitar da sinadarin polycyclic aromatic hydrocarbon (PAH) daga tushen noma mara tushe (Pingali, 2012; Duttagupta et al., 2020). An kiyasta kashi 55% (kadada 85,722,000) na jimillar filayen noma a Indiya ana yi musu maganin magungunan kashe kwari masu guba. A cikin shekaru biyar da suka gabata (2015-2020), fannin noma na Indiya ya yi amfani da matsakaicin tan 55,000 zuwa 60,000 na magungunan kashe kwari a kowace shekara (Ma'aikatar Hadin Gwiwa da Jin Dadin Manoma, Ma'aikatar Noma, Gwamnatin Indiya, Agusta 2020). A filayen arewa da tsakiyar Gangetic (jihohin da ke da yawan jama'a da yawan jama'a), amfani da magungunan kashe kwari a kan amfanin gona ya yadu, inda magungunan kwari suka fi yawa. Carbaryl (1-naphthyl-N-methylcarbamate) wani maganin kwari ne mai faɗi-faɗi, mai guba zuwa matsakaici mai yawa wanda ake amfani da shi a noma na Indiya a matsakaicin adadin tan 100-110. Ana sayar da shi a ƙarƙashin sunan kasuwanci Sevin kuma ana amfani da shi don sarrafa kwari (aphids, tururuwan wuta, ƙuma, ƙwari, gizo-gizo da sauran kwari da yawa na waje) waɗanda ke shafar nau'ikan amfanin gona (masara, waken soya, auduga, 'ya'yan itatuwa da kayan lambu). Wasu ƙwayoyin cuta kamar Pseudomonas (NCIB 12042, 12043, C4, C5, C6, C7, Pseudomonas putida XWY-1), Rhodococcus (NCIB 12038), Sphingobacterium spp. (CF06), Burkholderia (C3), Micrococcus da Arthrobacter suma ana iya amfani da su don sarrafa wasu kwari. An ruwaito cewa RC100 na iya lalata carbaryl (Larkin da Day, 1986; Chapalamadugu da Chaudhry, 1991; Hayatsu et al., 1999; Swetha da Phale, 2005; Trivedi et al., 2017). An yi nazari sosai kan hanyar lalata carbaryl a matakan biochemical, enzymatic da genetic a cikin keɓance ƙasa na Pseudomonas sp. Strains C4, C5 da C6 (Swetha da Phale, 2005; Trivedi et al., 2016) (Hoto na 3). Hanyar metabolism tana farawa ne da hydrolysis na haɗin ester ta hanyar carbaryl hydrolase (CH) don samar da 1-naphthol, methylamine da carbon dioxide. Daga nan sai a canza 1-naphthol zuwa 1,2-dihydroxynaphthalene ta hanyar 1-naphthol hydroxylase (1-NH), wanda ake ƙara metabolize ta hanyar hanyar carbon ta tsakiya ta hanyar salicylate da gentisate. An ruwaito cewa wasu ƙwayoyin cuta masu lalata carbaryl suna metabolize ta zuwa salicylic acid ta hanyar raba zoben catechol ortho (Larkin and Day, 1986; Chapalamadugu da Chaudhry, 1991). Abin lura shi ne, ƙwayoyin cuta masu lalata naphthalene galibi suna metabolize salicylic acid ta hanyar catechol, yayin da ƙwayoyin cuta masu lalata carbaryl suka fi son metabolize salicylic acid ta hanyar hanyar gentisate.
Ana iya amfani da abubuwan da aka samo daga acid naphthalenesulfonic/disulfonic acid da naphthylaminesulfonic acid a matsayin tsaka-tsaki wajen samar da rini na azo, sinadaran jika, masu wargazawa, da sauransu. Duk da cewa waɗannan mahaɗan suna da ƙarancin guba ga mutane, kimantawar guba ta cytotoxicity ta nuna cewa suna da illa ga kifi, daphnia da algae (Greim et al., 1994). An ruwaito wakilan nau'in Pseudomonas (nau'ikan A3, C22) suna fara metabolism ta hanyar hydroxylation sau biyu na zoben aromatic wanda ke ɗauke da rukunin sulfonic acid don samar da dihydrodiol, wanda aka ƙara canza shi zuwa 1,2-dihydroxynaphthalene ta hanyar raba rukunin sulfite ba zato ba tsammani (Brilon et al., 1981). Sakamakon 1,2-dihydroxynaphthalene ana canza shi ta hanyar hanyar naphthalene ta gargajiya, watau hanyar catechol ko gentisate (Hoto na 4). An nuna cewa aminonaphthalenesulfonic acid da hydroxynaphthalenesulfonic acid za a iya lalata su gaba ɗaya ta hanyar gaurayawan ƙwayoyin cuta tare da hanyoyin catabolic masu dacewa (Nortemann et al., 1986). An nuna cewa memba ɗaya na ƙungiyar yana kawar da aminonaphthalenesulfonic acid ko hydroxynaphthalenesulfonic acid ta hanyar 1,2-dioxygenation, yayin da aminosalicylate ko hydroxysalicylate ana sakin su cikin yanayin al'ada a matsayin metabolite na ƙarshe kuma daga baya wasu membobin ƙungiyar suka ɗauke su. Naphthalenedisulfonic acid yana da alaƙa da polar amma ba shi da kyau a lalata shi kuma saboda haka ana iya metabolize shi ta hanyoyi daban-daban. Desulfurization na farko yana faruwa ne yayin regioselective dihydroxylation na zoben aromatic da ƙungiyar sulfonic acid; Na biyu na desulfurization yana faruwa ne yayin hydroxylation na 5-sulfosalicylic acid ta hanyar salicylic acid 5-hydroxylase don samar da gentisic acid, wanda ke shiga tsakiyar hanyar carbon (Brilon et al., 1981) (Hoto na 4). Enzymes da ke da alhakin lalata naphthalene suma suna da alhakin metabolism na naphthalene sulfonate (Brilon et al., 1981; Keck et al., 2006).
Siffa ta 4. Hanyoyin da ke haifar da lalacewar naphthalene sulfonate. Lambobin da ke cikin da'irori suna wakiltar enzymes da ke da alhakin metabolism na naphthyl sulfonate, kama da enzymes da aka bayyana a Siffa ta 3.
Ƙananan ƙwayoyin PAHs (LMW-PAHs) suna da sauƙin ragewa, suna da saurin narkewa kuma ba sa narkewa sosai, don haka ba sa fuskantar lalacewa/lalacewa ta halitta. Duk da haka, ƙwayoyin cuta masu amfani da iskar oxygen suna iya oxidize ta ta hanyar shan iskar oxygen ta kwayoyin halitta (O2). Waɗannan enzymes galibi suna cikin ajin oxidoreductases kuma suna iya yin ayyuka daban-daban kamar su aromatic ring hydroxylation (mono- ko dihydroxylation), dehydrogenation da kuma yankewar zobe mai ƙanshi. Kayayyakin da aka samu daga waɗannan halayen suna cikin yanayin oxidation mafi girma kuma ana iya metabolize su cikin sauƙi ta hanyar hanyar carbon ta tsakiya (Phale et al., 2020). An ruwaito cewa enzymes a cikin hanyar lalacewa suna da sauƙin haifarwa. Ayyukan waɗannan enzymes yana da ƙasa ko kaɗan lokacin da aka girma ƙwayoyin halitta akan tushen carbon mai sauƙi kamar glucose ko acid na halitta. Tebur na 3 ya taƙaita nau'ikan enzymes daban-daban (oxygenases, hydrolases, dehydrogenases, oxidases, da sauransu) da ke da hannu a cikin metabolism na naphthalene da abubuwan da suka samo asali.
Tebur na 3. Halayen sinadarai na enzymes da ke da alhakin lalata naphthalene da abubuwan da suka samo asali.
Nazarin rediyo (18O2) ya nuna cewa haɗakar ƙwayoyin halitta O2 cikin zobba masu ƙanshi ta hanyar oxygenases shine mafi mahimmancin mataki wajen kunna ƙarin lalatawar wani abu (Hayaishi et al., 1955; Mason et al., 1955). Haɗa ƙwayar oxygen guda ɗaya (O) daga iskar oxygen (O2) zuwa cikin substrate yana farawa ne ta hanyar monooxygenases na ciki ko na waje (wanda kuma ake kira hydroxylases). Wani ƙwayar oxygen an rage shi zuwa ruwa. Exogenous monooxygenases suna rage flavin tare da NADH ko NADPH, yayin da a cikin endomonooxygenases flavin yana raguwa ta hanyar substrate. Matsayin hydroxylation yana haifar da bambancin samuwar samfura. Misali, salicylate 1-hydroxylase hydroxylates salicylic acid a matsayin C1, yana samar da catechol. A gefe guda kuma, salicylate 5-hydroxylase mai yawan sinadaran (wanda ke ɗauke da reductase, ferredoxin, da kuma subunits na oxygenase) yana hydroxylates salicylic acid a matsayin C5, yana samar da gentisic acid (Yamamoto et al., 1965).
Dioxygenases suna haɗa ƙwayoyin halitta guda biyu na O2 a cikin substrate. Dangane da samfuran da aka samar, an raba su zuwa dioxygenases masu zobe da dioxygenases masu yanke zobe. Dioxygenases masu zobe suna canza substrates masu aromatic zuwa cis-dihydrodiols (misali, naphthalene) kuma suna yaɗuwa a tsakanin ƙwayoyin cuta. Zuwa yanzu, an nuna cewa halittu masu ɗauke da dioxygenases masu zobe suna iya girma akan tushen carbon mai ƙanshi daban-daban, kuma waɗannan enzymes an rarraba su azaman NDO (naphthalene), toluene dioxygenase (TDO, toluene), da biphenyl dioxygenase (BPDO, biphenyl). Dukansu NDO da BDO na iya haɓaka hydroxylation na oxidation sau biyu da sarkar gefe na nau'ikan hydrocarbons masu aromatic polycyclic (toluene, nitrotoluene, xylene, ethylbenzene, naphthalene, biphenyl, fluorene, indole, methylnaphthalene, naphthalenesulfonate, phenanthrene, anthracene, acetophenone, da sauransu) (Boyd da Sheldrake, 1998; Phale et al., 2020). NDO tsarin abubuwa da yawa ne wanda ya ƙunshi oxidoreductase, ferredoxin, da kuma wani ɓangaren oxygenase mai aiki (Gibson da Subramanian, 1984; Resnick et al., 1996). Sashen catalytic na NDO ya ƙunshi babban subunit na α da ƙaramin subunit na β wanda aka shirya a cikin tsarin α3β3. NDO na cikin babban iyali na oxygenases kuma α-subunit ɗinsa ya ƙunshi wurin Rieske [2Fe-2S] da kuma ƙarfe mai kama da na mononuclear wanda ba shi da heme, wanda ke ƙayyade takamaiman substrate na NDO (Parales et al., 1998). Yawanci, a cikin zagayowar catalytic ɗaya, ana canja wurin electrons biyu daga rage pyridine nucleotide zuwa ion na Fe(II) a cikin wurin aiki ta hanyar reductase, ferredoxin da wurin Rieske. Daidaitattun abubuwan da ke ragewa suna kunna iskar oxygen ta kwayoyin halitta, wanda shine sharadin dihydroxylation na substrate (Ferraro et al., 2005). Zuwa yanzu, an tsarkake NDO kaɗan kuma an siffanta su dalla-dalla daga nau'ikan daban-daban kuma an yi nazarin sarrafa kwayoyin halitta na hanyoyin da ke da alaƙa da lalata naphthalene dalla-dalla (Resnick et al., 1996; Parales et al., 1998; Karlsson et al., 2003). Dioxygenases masu yanke zobe (enzymes masu yanke zobe na endo- ko ortho-ring da enzymes masu yanke zobe na exodiol- ko meta-ring) suna aiki akan mahaɗan aromatic masu hydroxylated. Misali, dioxygenase mai yanke zobe na ortho-ring shine catechol-1,2-dioxygenase, yayin da dioxygenase mai yanke zobe na meta-ring shine catechol-2,3-dioxygenase (Kojima et al., 1961; Nozaki et al., 1968). Baya ga oxygenases daban-daban, akwai kuma dehydrogenases daban-daban waɗanda ke da alhakin rage hydrogenation na aromatic dihydrodiols, alcohols da aldehydes da amfani da NAD+/NADP+ a matsayin masu karɓar electrons, waɗanda wasu daga cikin mahimman enzymes ne da ke da hannu a cikin metabolism (Gibson da Subramanian, 1984; Shaw da Harayama, 1990; Fahle et al., 2020).
Enzymes kamar hydrolases (esterases, amidases) sune aji na biyu mai mahimmanci na enzymes waɗanda ke amfani da ruwa don raba haɗin covalent da kuma nuna takamaiman substrate. Ana ɗaukar Carbaryl hydrolase da sauran hydrolases a matsayin sassan periplasm (transmembrane) a cikin membobin ƙwayoyin cuta na Gram-negative (Kamini et al., 2018). Carbaryl yana da haɗin amide da ester; saboda haka, ana iya haɗa shi ta hanyar esterase ko amidase don samar da 1-naphthol. An ruwaito cewa Carbaryl a cikin Rhizobium rhizobium nau'in AC10023 da Arthrobacter nau'in RC100 suna aiki azaman esterase da amidase, bi da bi. Carbaryl a cikin nau'in Arthrobacter RC100 shima yana aiki azaman amidase. An nuna cewa RC100 yana samar da hydrolyzes na kwari guda huɗu na N-methylcarbamate kamar carbaryl, methomyl, mefenamic acid da XMC (Hayaatsu et al., 2001). An ruwaito cewa CH a cikin Pseudomonas sp. C5pp na iya aiki akan carbaryl (aikin 100%) da 1-naphthyl acetate (aikin 36%), amma ba akan 1-naphthylacetamide ba, yana nuna cewa esterase ne (Trivedi et al., 2016).
Nazarin sinadarai, tsarin daidaita enzyme, da kuma nazarin kwayoyin halitta sun nuna cewa kwayoyin halittar naphthalene na lalacewa sun ƙunshi raka'o'i biyu masu sarrafawa ko "operons": nah ("hanyar sama", tana canza naphthalene zuwa salicylic acid) da sal ("hanyar ƙasa", tana canza salicylic acid zuwa hanyar carbon ta tsakiya ta hanyar catechol). Salicylic acid da analogues ɗinsa na iya aiki a matsayin masu haifar da (Shamsuzzaman da Barnsley, 1974). A gaban glucose ko acid na halitta, ana danne operon. Hoto na 5 yana nuna cikakken tsarin kwayoyin halitta na lalata naphthalene (a cikin siffar operon). An bayyana nau'ikan/siffofi da yawa na kwayar halittar nah (ndo/pah/dox) kuma an gano suna da babban tsari (90%) tsakanin dukkan nau'ikan Pseudomonas (Abbasian et al., 2016). An tsara kwayoyin halittar naphthalene ta hanyar sama gaba ɗaya a cikin tsari na yarjejeniya kamar yadda aka nuna a Hoto na 5A. An kuma ruwaito cewa wata kwayar halitta, nahQ, tana da hannu a cikin metabolism na naphthalene kuma yawanci tana tsakanin nahC da nahE, amma ainihin aikinsa har yanzu ba a fayyace shi ba. Hakazalika, an sami kwayar halittar nahY, wacce ke da alhakin chemotaxis mai saurin kamuwa da naphthalene, a ƙarshen nah operon a wasu membobi. A cikin Ralstonia sp., an gano cewa kwayar halittar U2 mai ɓoye glutathione S-transferase (gsh) tana tsakanin nahAa da nahAb amma ba ta shafi halayen amfani da naphthalene ba (Zylstra et al., 1997).
Hoto na 5. Tsarin kwayoyin halitta da bambancin da aka lura yayin lalacewar naphthalene tsakanin nau'ikan ƙwayoyin cuta; (A) Hanyar naphthalene ta sama, metabolism na naphthalene zuwa salicylic acid; (B) Hanyar naphthalene ta ƙasa, salicylic acid ta hanyar catechol zuwa hanyar carbon ta tsakiya; (C) salicylic acid ta hanyar gentisate zuwa hanyar carbon ta tsakiya.
"Ƙasa hanya" (sal operon) yawanci ya ƙunshi nahGTHINLMOKJ kuma yana canza salicylate zuwa pyruvate da acetaldehyde ta hanyar hanyar catechol metaring cleavage. An gano cewa kwayar halittar nahG (mai ɓoye salicylate hydroxylase) tana nan a ƙarshen operon (Hoto na 5B). Idan aka kwatanta da sauran nau'ikan naphthalene-degrading, a cikin P. putida CSV86 nah da sal operons suna da alaƙa mai kama da juna (kimanin 7.5 kb). A cikin wasu ƙwayoyin cuta masu kama da Gram-negative, kamar Ralstonia sp. U2, Polaromonas naphthalenivorans CJ2, da P. putida AK5, naphthalene ana metabolized azaman tsakiyar carbon metabolite ta hanyar hanyar gentisate (a cikin siffar sgp/nag operon). Ana nuna kaset ɗin kwayar halitta a cikin nau'in nagAaGHabAcAdBFCQEDJI, inda nagR (mai shigar da mai sarrafa nau'in LysR) yake a ƙarshen sama (Hoto na 5C).
Carbaryl yana shiga cikin zagayowar carbon ta tsakiya ta hanyar metabolism na 1-naphthol, 1,2-dihydroxynaphthalene, salicylic acid, da gentisic acid (Hoto na 3). Dangane da nazarin kwayoyin halitta da na rayuwa, an gabatar da shawarar raba wannan hanyar zuwa "sama" (canza carbaryl zuwa salicylic acid), "tsakiya" (canza salicylic acid zuwa gentisic acid), da kuma "ƙasa" (canza gentisic acid zuwa tsakiyar hanyar carbon ta tsakiya) (Singh et al., 2013). Binciken kwayoyin halitta na C5pp (supercontig A, 76.3 kb) ya nuna cewa kwayar halittar mcbACBDEF tana da hannu a cikin canza carbaryl zuwa salicylic acid, sannan mcbIJKL ta biyo baya wajen canza salicylic acid zuwa gentisic acid, da kuma mcbOQP ta hanyar canza gentisic acid zuwa tsakiyar carbon (fumarate da pyruvate, Trivedi et al., 2016) (Hoto na 6).
An ruwaito cewa enzymes da ke da hannu wajen lalata sinadarin hydrocarbons masu kamshi (gami da naphthalene da salicylic acid) za a iya haifar da su ta hanyar mahaɗan da suka dace kuma a hana su ta hanyar hanyoyin carbon masu sauƙi kamar glucose ko Organic acid (Shingler, 2003; Phale et al., 2019, 2020). Daga cikin hanyoyin metabolism daban-daban na naphthalene da abubuwan da suka samo asali, an yi nazarin siffofin tsari na naphthalene da carbaryl har zuwa wani mataki. Ga naphthalene, kwayoyin halitta a cikin hanyoyin sama da ƙasa ana sarrafa su ta hanyar NahR, wani mai daidaita yanayin aiki na LysR. Ana buƙatar sa don haifar da kwayar halittar nah ta hanyar salicylic acid da kuma bayyanarsa mai girma (Yen da Gunsalus, 1982). Bugu da ƙari, bincike ya nuna cewa haɗin gwiwar mai masaukin baki (IHF) da XylR (sigma 54-dependent transcriptional regulator) suma suna da mahimmanci don kunna kwayoyin halitta a cikin metabolism na naphthalene (Ramos et al., 1997). Nazarin ya nuna cewa enzymes na hanyar buɗewar meta-ring ta catechol, wato catechol 2,3-dioxygenase, ana haifar da su ne a gaban naphthalene da/ko salicylic acid (Basu et al., 2006). Nazarin ya nuna cewa enzymes na hanyar buɗewar catechol ortho-ring, wato catechol 1,2-dioxygenase, ana haifar da su ne a gaban benzoic acid da cis,cis-muconate (Parsek et al., 1994; Tover et al., 2001).
A cikin nau'in C5pp, kwayoyin halitta guda biyar, mcbG, mcbH, mcbN, mcbR da mcbS, suna sanya masu kula da kwayoyin halitta na dangin LysR/TetR na masu kula da kwayoyin halitta da ke da alhakin sarrafa lalacewar carbaryl. An gano cewa kwayar halittar mcbG mai kama da juna tana da alaƙa da mai kula da nau'in LysR PhnS (kashi 58% na asalin amino acid) da ke da hannu a cikin metabolism na phenanthrene a cikin Burkholderia RP00725 (Trivedi et al., 2016). An gano cewa kwayar halittar mcbH tana da hannu a cikin hanyar tsaka-tsaki (canza salicylic acid zuwa gentisic acid) kuma tana cikin mai kula da kwayoyin halitta na LysR NagR/DntR/NahR a cikin Pseudomonas da Burkholderia. An ruwaito cewa membobin wannan iyali sun gane salicylic acid a matsayin wani takamaiman kwayar halitta mai tasiri don haifar da kwayoyin halitta masu lalacewa. A gefe guda kuma, an gano kwayoyin halitta guda uku, mcbN, mcbR da mcbS, waɗanda ke cikin masu kula da nau'in LysR da TetR, a cikin hanyar da ke ƙasa (metabolites na hanyar carbon ta gentisate-central).
A cikin prokaryotes, hanyoyin canja wurin kwayoyin halitta a kwance (samowa, musanya, ko canja wurin) ta hanyar plasmids, transposons, prophages, genomic Islands, da integrative conjugative elements (ICE) sune manyan abubuwan da ke haifar da plasticity a cikin kwayoyin halittar ƙwayoyin cuta, wanda ke haifar da samun ko asarar takamaiman ayyuka/halaye. Yana bawa ƙwayoyin cuta damar daidaitawa da sauri zuwa ga yanayi daban-daban na muhalli, yana samar da yuwuwar fa'idodin metabolism ga mai masaukin baki, kamar lalata mahaɗan aromatic. Sau da yawa ana samun canje-canje na metabolism ta hanyar daidaita lalacewar operons, hanyoyin sarrafa su, da takamaiman enzyme, wanda ke sauƙaƙe lalata nau'ikan mahaɗan aromatic (Nojiri et al., 2004; Phale et al., 2019, 2020). An gano cewa kaset ɗin kwayoyin halitta don lalata naphthalene suna kan abubuwa daban-daban na hannu kamar plasmids (conjugative da non-conjugative), transposons, genoms, ICEs, da haɗuwa da nau'ikan ƙwayoyin cuta daban-daban (Hoto na 5). A cikin Pseudomonas G7, an rubuta nah da sal operons na plasmid NAH7 a daidai wannan yanayin kuma suna cikin transposon mai lahani wanda ke buƙatar transposase Tn4653 don motsa jiki (Sota et al., 2006). A cikin nau'in Pseudomonas NCIB9816-4, an sami kwayar halittar akan plasmid conjugative pDTG1 a matsayin operons biyu (kimanin 15 kb a tsakaninsu) waɗanda aka rubuta su a cikin kwatance daban-daban (Dennis da Zylstra, 2004). A cikin nau'in Pseudomonas putida AK5, plasmid mara haɗin gwiwa pAK5 yana ɓoye enzyme wanda ke da alhakin lalata naphthalene ta hanyar hanyar gentisate (Izmalkova et al., 2013). A cikin nau'in Pseudomonas PMD-1, nah operon yana kan chromosome, yayin da sal operon yana kan plasmid conjugative pMWD-1 (Zuniga et al., 1981). Duk da haka, a cikin Pseudomonas stutzeri AN10, duk kwayoyin halittar naphthalene (nah da sal operons) suna kan chromosome kuma ana iya ɗaukar su ta hanyar transposition, recombination, da reorganization events (Bosch et al., 2000). A cikin Pseudomonas sp. CSV86, nah da sal operon suna cikin genome a cikin nau'in ICE (ICECSV86). Tsarin yana da kariya ta hanyar tRNAGly wanda ke biyo baya tare da maimaitawa kai tsaye wanda ke nuna wuraren haɗuwa/haɗewa (attR da attL) da haɗin kai mai kama da phage wanda ke a ƙarshen tRNAGly biyu, don haka yana kama da sinadarin ICEclc (ICEclcB13 a cikin Pseudomonas knackmusii don lalata chlorocatechol). An ruwaito cewa ana iya canja wurin kwayoyin halitta akan ICE ta hanyar haɗuwa tare da ƙarancin mitar canja wuri (10-8), ta haka ana canja wurin kaddarorin lalacewa ga mai karɓa (Basu da Phale, 2008; Phale et al., 2019).
Yawancin kwayoyin halittar da ke da alhakin lalata carbaryl suna kan ƙwayoyin plasmids. Arthrobacter sp. RC100 ya ƙunshi ƙwayoyin plasmids guda uku (pRC1, pRC2 da pRC300) waɗanda plasmids guda biyu masu haɗin gwiwa, pRC1 da pRC2, suna samar da enzymes waɗanda ke canza carbaryl zuwa gentisate. A gefe guda kuma, enzymes da ke da hannu wajen canza gentisate zuwa metabolites na carbon na tsakiya suna kan chromosome (Hayaatsu et al., 1999). Kwayoyin cuta na halittar Rhizobium. Tsarin AC100, wanda aka yi amfani da shi don canza carbaryl zuwa 1-naphthol, yana ɗauke da ƙwayoyin plasmid pAC200, wanda ke ɗauke da kwayar halittar cehA mai suna CH a matsayin wani ɓangare na transposon na Tnceh wanda ke kewaye da jerin abubuwan da aka saka (istA da istB) (Hashimoto et al., 2002). A cikin nau'in Sphingomonas CF06, ana kyautata zaton kwayar halittar lalata carbaryl tana cikin ƙwayoyin plasmids guda biyar: pCF01, pCF02, pCF03, pCF04, da pCF05. Daidaiton DNA na waɗannan ƙwayoyin plasmids yana da yawa, yana nuna wanzuwar wani lamari na kwafi na kwayar halitta (Feng et al., 1997). A cikin wani simbiont mai lalata carbaryl wanda ya ƙunshi nau'ikan Pseudomonas guda biyu, nau'in 50581 ya ƙunshi ƙwayar plasmid mai haɗuwa pCD1 (50 kb) wanda ke ɓoye kwayar halittar mcd carbaryl hydrolase, yayin da ƙwayar plasmid mai haɗuwa a cikin nau'in 50552 ta ɓoye enzyme mai lalata 1-naphthol (Chapalamadugu da Chaudhry, 1991). A cikin nau'in Achromobacter WM111, kwayar halittar mcd furadan hydrolase tana kan ƙwayar plasmid mai 100 kb (pPDL11). An nuna cewa wannan kwayar halitta tana nan a kan ƙwayoyin cuta daban-daban (100, 105, 115 ko 124 kb) a cikin ƙwayoyin cuta daban-daban daga yankuna daban-daban na ƙasa (Parekh et al., 1995). A cikin Pseudomonas sp. C5pp, duk kwayoyin halitta da ke da alhakin lalata carbaryl suna cikin kwayar halitta mai tsawon 76.3 kb na jerin abubuwa (Trivedi et al., 2016). Binciken kwayoyin halitta (6.15 Mb) ya bayyana kasancewar MGE 42 da GEI 36, waɗanda daga cikinsu MGE 17 suna cikin supercontig A (76.3 kb) tare da matsakaicin abun ciki na G+C mara daidaituwa (54–60 mol%), yana nuna yiwuwar abubuwan da suka faru na canja wurin kwayar halitta a kwance (Trivedi et al., 2016). P. putida XWY-1 yana nuna irin wannan tsari na kwayoyin halitta masu lalata carbaryl, amma waɗannan kwayoyin halitta suna kan plasmid (Zhu et al., 2019).
Baya ga ingancin metabolism a matakan biochemical da genomic, ƙananan halittu kuma suna nuna wasu halaye ko martani kamar chemotaxis, halayen gyaran saman tantanin halitta, rarrabuwa, amfani da fifiko, samar da biosurfactant, da sauransu, wanda ke taimaka musu wajen sarrafa gurɓatattun abubuwa masu ƙamshi yadda ya kamata a muhallin da aka gurbata (Hoto na 7).
Hoto na 7. Dabaru daban-daban na martanin ƙwayoyin cuta masu ƙamshi masu lalata hydrocarbon don ingantaccen lalata ƙwayoyin cuta na gurɓataccen iska na ƙasashen waje.
Ana ɗaukar martanin chemotactic a matsayin abubuwan da ke ƙara lalacewar gurɓatattun abubuwa na halitta a cikin yanayin halittu masu gurɓataccen yanayi daban-daban. (2002) ya nuna cewa chemotaxis na Pseudomonas sp. G7 zuwa naphthalene ya ƙara yawan lalacewar naphthalene a cikin tsarin ruwa. Nau'in daji na G7 ya lalata naphthalene da sauri fiye da nau'in maye gurɓataccen chemotaxis. An gano cewa furotin NahY (amino acid 538 tare da membrane topology) an haɗa shi tare da kwayoyin halittar hanyar metacleavage akan plasmid na NAH7, kuma kamar masu canza chemotaxis, wannan furotin yana aiki azaman mai karɓar chemoreceptor don lalata naphthalene (Grimm da Harwood 1997). Wani bincike da Hansel et al. (2009) suka yi ya nuna cewa furotin yana da chemotactic, amma ƙimar lalacewarsa tana da yawa. (2011) sun nuna martanin chemotactic na Pseudomonas (P. putida) ga gas naphthalene, inda yaduwar yanayin iskar gas ya haifar da kwararar naphthalene zuwa ƙwayoyin halitta, wanda ke sarrafa amsawar chemotactic na ƙwayoyin halitta. Masu binciken sun yi amfani da wannan ɗabi'ar chemotactic don ƙirƙirar ƙwayoyin cuta waɗanda za su haɓaka saurin lalacewa. Nazarin ya nuna cewa hanyoyin chemosensory kuma suna tsara wasu ayyukan ƙwayoyin halitta kamar rarraba ƙwayoyin halitta, daidaita zagayowar ƙwayoyin halitta, da samuwar biofilm, don haka suna taimakawa wajen sarrafa saurin lalacewa. Duk da haka, amfani da wannan siffa (chemotaxis) don ingantaccen lalacewa yana da cikas saboda matsaloli da yawa. Manyan cikas sune: (a) masu karɓar paralogous daban-daban suna gane mahaɗan/ligands iri ɗaya; (b) wanzuwar madadin masu karɓar, watau, tropism mai kuzari; (c) bambance-bambancen jerin abubuwa masu mahimmanci a cikin sassan ji na iyali mai karɓar guda ɗaya; da (d) rashin bayanai game da manyan sunadaran firikwensin ƙwayoyin cuta (Ortega et al., 2017; Martin-Mora et al., 2018). Wani lokaci, lalacewar sinadaran aromatic hydrocarbons yana samar da metabolites/matsakaici da yawa, wanda zai iya zama mai guba ga rukuni ɗaya na ƙwayoyin cuta amma yana da ƙyama ga wasu, wanda hakan ke ƙara rikitar da tsarin. Don gano hulɗar ligands (ƙanshi hydrocarbons) da masu karɓar sinadarai, mun gina sunadaran firikwensin masu haɗaka (PcaY, McfR, da NahY) ta hanyar haɗa sassan firikwensin da siginar Pseudomonas putida da Escherichia coli, waɗanda ke niyya ga masu karɓar acid mai ƙanshi, tsaka-tsakin TCA, da naphthalene, bi da bi (Luu et al., 2019).
A ƙarƙashin tasirin naphthalene da sauran polycyclic aromatic hydrocarbons (PAHs), tsarin membrane na ƙwayoyin cuta da kuma ingancin ƙwayoyin cuta suna fuskantar manyan canje-canje. Bincike ya nuna cewa naphthalene yana tsoma baki ga hulɗar sarkar acyl ta hanyar hulɗar hydrophobic, ta haka yana ƙara kumburi da ruwa na membrane (Sikkema et al., 1995). Don magance wannan mummunan tasirin, ƙwayoyin cuta suna daidaita ruwa na membrane ta hanyar canza rabo da abun da ke cikin fatty acid tsakanin iso/anteiso branched-chain fatty acids da isomerizing cis-unsaturated fatty acids zuwa cikin trans-isomers masu dacewa (Heipieper da de Bont, 1994). A cikin Pseudomonas stutzeri da aka girma akan maganin naphthalene, rabon fatty acid mai cike da kitse ya ƙaru daga 1.1 zuwa 2.1, yayin da a cikin Pseudomonas JS150 wannan rabo ya ƙaru daga 7.5 zuwa 12.0 (Mrozik et al., 2004). Lokacin da aka girma a kan naphthalene, ƙwayoyin Achromobacter KAs 3–5 sun nuna tarin ƙwayoyin halitta a kusa da lu'ulu'u naphthalene da raguwar cajin saman tantanin halitta (daga -22.5 zuwa -2.5 mV) tare da haɗuwa da cytoplasmic da vacuolization, wanda ke nuna canje-canje a cikin tsarin tantanin halitta da halayen saman tantanin halitta (Mohapatra et al., 2019). Duk da cewa canje-canjen tantanin halitta/fuska suna da alaƙa kai tsaye da ingantaccen ɗaukar gurɓatattun ƙamshi, dabarun injiniyan halittu masu dacewa ba a inganta su sosai ba. Ba kasafai ake amfani da sarrafa siffar tantanin halitta don inganta hanyoyin halittu ba (Volke da Nikel, 2018). Share kwayoyin halitta da ke shafar rarraba tantanin halitta yana haifar da canje-canje a cikin yanayin tantanin halitta. Share kwayoyin halitta da ke shafar rarraba tantanin halitta yana haifar da canje-canje a cikin yanayin tantanin halitta. A cikin Bacillus subtilis, an nuna cewa furotin septum na tantanin halitta SepF yana da hannu a cikin samuwar septum kuma ana buƙatar shi don matakai na gaba na rarraba tantanin halitta, amma ba kwayar halitta ce mai mahimmanci ba. Share kwayoyin halittar da ke dauke da peptide glycan hydrolases a cikin Bacillus subtilis ya haifar da tsawaitar tantanin halitta, karuwar takamaiman saurin girma, da kuma inganta karfin samar da enzyme (Cui et al., 2018).
An gabatar da raba hanyar lalata carbaryl don cimma ingantaccen lalata nau'ikan Pseudomonas C5pp da C7 (Kamini et al., 2018). An ba da shawarar cewa a jigilar carbaryl zuwa sararin periplasmic ta cikin septum na membrane na waje da/ko ta hanyar porins masu yaɗuwa. CH wani enzyme ne na periplasmic wanda ke haɓaka hydrolysis na carbaryl zuwa 1-naphthol, wanda ya fi karko, ya fi hydrophobic kuma ya fi guba. CH yana cikin periplasm kuma yana da ƙarancin kusanci ga carbaryl, don haka yana sarrafa samuwar 1-naphthol, don haka yana hana taruwarsa a cikin ƙwayoyin halitta da rage gubarsa ga ƙwayoyin halitta (Kamini et al., 2018). Ana jigilar 1-naphthol da ya haifar zuwa cikin cytoplasm a cikin membrane na ciki ta hanyar rabawa da/ko yaɗuwa, sannan a haɗa shi da hydroxylated zuwa 1,2-dihydroxynaphthalene ta hanyar enzyme mai haɗin kai 1NH don ƙarin metabolism a cikin hanyar carbon ta tsakiya.
Duk da cewa ƙananan halittu suna da ikon kwayoyin halitta da kuma na rayuwa don rage tushen carbon na xenobiotic, tsarin tsari na amfani da su (watau, amfani da tushen carbon mai sauƙi fiye da hadaddun) babban cikas ne ga lalacewar halittu. Kasancewa da amfani da tushen carbon mai sauƙi yana rage kwayoyin halittar da ke ɗauke da enzymes waɗanda ke lalata tushen carbon mai rikitarwa/marasa fifiko kamar PAHs. Misali da aka yi nazari sosai shine lokacin da aka haɗu da glucose da lactose zuwa Escherichia coli, ana amfani da glucose yadda ya kamata fiye da lactose (Jacob da Monod, 1965). An ruwaito cewa Pseudomonas yana lalata nau'ikan PAHs da mahaɗan xenobiotic a matsayin tushen carbon. Tsarin amfani da tushen carbon a cikin Pseudomonas shine acid na halitta > glucose > mahaɗan aromatic (Hylemon da Phibbs, 1972; Collier et al., 1996). Duk da haka, akwai banda. Abin sha'awa, Pseudomonas sp. CSV86 yana nuna wani tsari na musamman wanda yafi amfani da sinadaran aromatic hydrocarbons (benzoic acid, naphthalene, da sauransu) maimakon glucose kuma yana haɗa sinadarin aromatic hydrocarbons tare da acid na organic (Basu et al., 2006). A cikin wannan ƙwayar cuta, ba a rage tsarin kwayoyin halittar da ake amfani da su don lalata da jigilar sinadarin aromatic hydrocarbons ko da a gaban tushen carbon na biyu kamar glucose ko acid na organic. Lokacin da aka girma a cikin glucose da matsakaici na hydrocarbons na aromatic, an lura cewa an rage tsarin kwayoyin halittar jigilar glucose da metabolism, an yi amfani da hydrocarbons na aromatic a matakin log na farko, kuma an yi amfani da glucose a matakin log na biyu (Basu et al., 2006; Choudhary et al., 2017). A gefe guda kuma, kasancewar sinadaran organic bai shafi bayyanar sinadaran aromatic hydrocarbon ba, don haka ana sa ran wannan ƙwayar cuta za ta zama nau'in da za a yi amfani da shi don nazarin lalacewar halittu (Phale et al., 2020).
An san cewa canjin yanayin hydrocarbon na iya haifar da damuwa ta oxidative da kuma ƙaruwar enzymes na antioxidant a cikin ƙwayoyin cuta. Rashin ingantaccen naphthalene biograderation duka a cikin ƙwayoyin halitta masu tsayi da kuma kasancewar sinadarai masu guba yana haifar da samuwar nau'in oxygen mai amsawa (ROS) (Kang et al. 2006). Tunda enzymes masu lalata naphthalene suna ɗauke da tarin ƙarfe-sulfur, a ƙarƙashin matsin lamba na oxidative, ƙarfe a cikin heme da furotin-sulfur za a yi oxidize, wanda ke haifar da rashin aiki na furotin. Ferredoxin-NADP+ reductase (Fpr), tare da superoxide dismutase (SOD), yana daidaita amsawar redox mai juyawa tsakanin NADP+/NADPH da ƙwayoyin ferredoxin ko flavodoxin guda biyu, ta haka yana kawar da ROS da dawo da cibiyar ƙarfe-sulfur a ƙarƙashin matsin lamba na oxidative (Li et al. 2006). An ruwaito cewa Fpr da SodA (SOD) a cikin Pseudomonas na iya haifar da damuwa ta oxidative, kuma an lura da ƙaruwar ayyukan SOD da catalase a cikin nau'ikan Pseudomonas guda huɗu (O1, W1, As1, da G1) yayin girma a ƙarƙashin yanayin da aka ƙara naphthalene (Kang et al., 2006). Nazarin ya nuna cewa ƙara antioxidants kamar ascorbic acid ko ferrous iron (Fe2+) na iya ƙara yawan girma naphthalene. Lokacin da Rhodococcus erythropolis ya girma a cikin matsakaici na naphthalene, an ƙara kwafin kwayoyin halittar cytochrome P450 masu alaƙa da oxidative stress ciki har da sodA (Fe/Mn superoxide dismutase), sodC (Cu/Zn superoxide dismutase), da recA (Sazykin et al., 2019). Binciken kwatancen adadi na proteomic na ƙwayoyin Pseudomonas da aka noma a cikin naphthalene ya nuna cewa haɓaka furotin daban-daban da ke da alaƙa da amsawar damuwa ta oxidative dabara ce ta magance damuwa (Herbst et al., 2013).
An ruwaito cewa ƙananan halittu suna samar da halittu masu rai a ƙarƙashin tasirin tushen carbon mai hana ruwa. Waɗannan surfactants mahaɗan amphiphilic ne masu aiki a saman amphiphilic waɗanda zasu iya samar da tarawa a mahaɗan mai-ruwa ko iska-ruwa. Wannan yana haɓaka narkewar abubuwa kuma yana sauƙaƙa shaƙar hydrocarbons masu ƙanshi, wanda ke haifar da lalacewar halittu masu rai (Rahman et al., 2002). Saboda waɗannan kaddarorin, ana amfani da biosurfactants sosai a masana'antu daban-daban. Ƙara sinadaran surfactants ko biosurfactants zuwa al'adun ƙwayoyin cuta na iya haɓaka inganci da saurin lalacewar hydrocarbon. Daga cikin biosurfactants, an yi nazari sosai kuma an siffanta rhamnolipids da Pseudomonas aeruginosa suka samar (Hisatsuka et al., 1971; Rahman et al., 2002). Bugu da ƙari, wasu nau'ikan biosurfactants sun haɗa da lipopeptides (mucins daga Pseudomonas fluorescens), emulsifier 378 (daga Pseudomonas fluorescens) (Rosenberg da Ron, 1999), lipids na trehalose disaccharide daga Rhodococcus (Ramdahl, 1985), lichenin daga Bacillus (Saraswathy da Hallberg, 2002), da kuma surfactant daga Bacillus subtilis (Siegmund da Wagner, 1991) da Bacillus amyloliquefaciens (Zhi et al., 2017). An nuna cewa waɗannan surfactants masu ƙarfi suna rage tashin hankali daga dynes 72/cm zuwa ƙasa da dynes 30/cm, wanda ke ba da damar samun ingantaccen sha na hydrocarbon. An ruwaito cewa Pseudomonas, Bacillus, Rhodococcus, Burkholderia da sauran nau'ikan ƙwayoyin cuta na iya samar da nau'ikan halittu masu kama da rhamnolipid da glycolipid lokacin da aka girma a cikin naphthalene da methylnaphthalene media (Kanga et al., 1997; Puntus et al., 2005). Pseudomonas maltophilia CSV89 na iya samar da biosurfactant na extracellular Biosur-Pm lokacin da aka girma akan mahaɗan aromatic kamar naphthoic acid (Phale et al., 1995). Kinetics na samuwar Biosur-Pm ya nuna cewa haɗinsa tsari ne na girma da dogaro da pH. An gano cewa adadin Biosur-Pm da ƙwayoyin halitta ke samarwa a pH tsaka tsaki ya fi na pH 8.5. Kwayoyin da aka girma a pH 8.5 sun fi hydrophobic kuma suna da alaƙa mafi girma ga mahaɗan aromatic da aliphatic fiye da ƙwayoyin da aka girma a pH 7.0. A cikin Rhodococcus spp. N6, mafi girman rabon carbon zuwa nitrogen (C:N) da kuma iyakancewar ƙarfe sune mafi kyawun yanayi don samar da biosurfactants na waje (Mutalik et al., 2008). An yi ƙoƙarin inganta biosynthesis na biosurfactants (surfactins) ta hanyar inganta nau'ikan da kuma fermentation. Duk da haka, titer na surfactant a cikin yanayin al'ada yana da ƙasa (1.0 g/L), wanda ke haifar da ƙalubale ga samar da babban girma (Jiao et al., 2017; Wu et al., 2019). Saboda haka, an yi amfani da hanyoyin injiniyan kwayoyin halitta don inganta biosynthesis ɗinsa. Duk da haka, gyaran injiniyancinsa yana da wahala saboda girman operon (kimanin 25 kb) da kuma tsarin biosynthesis mai rikitarwa na tsarin ji na quorum (Jiao et al., 2017; Wu et al., 2019). An gudanar da gyare-gyare da dama na injiniyancin kwayoyin halitta a cikin ƙwayoyin cuta na Bacillus, waɗanda aka fi mayar da hankali a kansu don ƙara yawan samar da surfactin ta hanyar maye gurbin mai haɓaka (srfA operon), ƙara yawan furotin na fitar da surfactin YerP da abubuwan da ke daidaita ComX da PhrC (Jiao et al., 2017). Duk da haka, waɗannan hanyoyin injiniyancin kwayoyin halitta sun cimma sau ɗaya ko kaɗan na gyare-gyaren kwayoyin halitta kuma har yanzu ba su kai ga samar da kasuwanci ba. Saboda haka, ƙarin bincike kan hanyoyin ingantawa bisa ga ilimi ya zama dole.
Ana gudanar da nazarin lalata ƙwayoyin halitta na PAH galibi a ƙarƙashin yanayin dakin gwaje-gwaje na yau da kullun. Duk da haka, a wuraren da suka gurɓata ko a cikin muhallin da suka gurɓata, an nuna cewa abubuwa da yawa masu hana ƙwayoyin cuta da kuma abubuwan da ke haifar da ƙwayoyin cuta (zafin jiki, pH, iskar oxygen, samuwar sinadarai, samuwar ƙwayoyin cuta, sauran ƙwayoyin cuta masu haɗari, hana samfuran ƙarshe, da sauransu) suna canzawa da kuma tasiri ga ƙarfin lalata ƙwayoyin cuta.
Zafin jiki yana da tasiri sosai ga lalacewar PAH. Yayin da zafin jiki ke ƙaruwa, yawan iskar oxygen da ke narkewa yana raguwa, wanda ke shafar metabolism na ƙwayoyin cuta masu amfani da iskar oxygen, tunda suna buƙatar iskar oxygen ta kwayoyin halitta a matsayin ɗaya daga cikin abubuwan da ke haifar da iskar oxygen waɗanda ke aiwatar da halayen hydroxylation ko ring cleavage. Sau da yawa ana lura cewa yawan zafin jiki yana canza PAHs na iyaye zuwa wasu sinadarai masu guba, ta haka yana hana lalacewar biograde (Muller et al., 1998).
An lura cewa wurare da yawa da suka gurɓata daga PAH suna da ƙimar pH mai tsanani, kamar wuraren da aka gurɓata daga magudanar ruwa ta acid (pH 1–4) da wuraren gas/kwal na halitta da aka gurɓata da alkaline leachate (pH 8–12). Waɗannan yanayi na iya yin tasiri sosai ga tsarin lalata ƙwayoyin halitta. Saboda haka, kafin amfani da ƙananan halittu don gyara ƙwayoyin halitta, ana ba da shawarar a daidaita pH ta hanyar ƙara sinadarai masu dacewa (tare da matsakaicin zuwa ƙarancin rage oxidation) kamar ammonium sulfate ko ammonium nitrate don ƙasa alkaline ko liming tare da calcium carbonate ko magnesium carbonate don wuraren acidic (Bowlen et al. 1995; Gupta da Sar 2020).
Samar da iskar oxygen ga yankin da abin ya shafa shine abin da ke iyakance saurin lalacewa ga PAH. Saboda yanayin redox na muhalli, hanyoyin gyaran halittu na in situ yawanci suna buƙatar shigar da iskar oxygen daga tushen waje (zubar da ruwa, fitar da iska, da ƙara sinadarai) (Pardieck et al., 1992). Odenkranz et al. (1996) sun nuna cewa ƙara magnesium peroxide (wani abu mai sakin iskar oxygen) zuwa cikin gurɓataccen ruwa zai iya magance mahaɗan BTEX yadda ya kamata. Wani bincike ya binciki lalacewar phenol da BTEX a cikin gurɓataccen ruwa ta hanyar allurar sodium nitrate da gina rijiyoyin fitar da iska don cimma ingantaccen gyaran halittu (Bewley da Webb, 2001).