Biodegradation of hexachlorocyclohexane-isomers in contaminated soils

Kumar, Manish; Gupta, S.K.; Garg, Shweta; Kumar, Ashwani

doi:10.1016/j.soilbio.2006.02.010

Cited by 52 publications

(28 citation statements)

References 38 publications

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“…A close analysis revealed that the LinB enzymes of Spϩ and UT26 differ from each other by three amino acids and that LinB of B90A differs from those of Spϩ and UT26 by six and seven amino acids residues, respectively. These differences in amino acids are outside the putative catalytic domain (D-108, H-272, and E-132) (7,11,17,18,22,27,28,33,34,37,40,47), but they seem to play an important role in the substrate specificity of the enzymes. Although the studies with purified LinB proteins from B90A and Spϩ are preliminary, they strongly indicate that strain B90A is best suited for biodegradation of ␤-HCH, the most recalcitrant isomer.…”

Section: Discussionmentioning

confidence: 99%

Haloalkane Dehalogenase LinB Is Responsible for β- and δ-Hexachlorocyclohexane Transformation inSphingobium indicumB90A

Sharma

Raina

Kumari

et al. 2006

Appl Environ Microbiol

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Incubation of resting cells of Sphingobium indicum B90A, Sphingobium japonicum UT26, and Sphingobium francense Sp؉ showed that they were able to transform ␤-and ␦-hexachlorocyclohexane (␤-and ␦-HCH, respectively), the most recalcitrant hexachlorocyclohexane isomers, to pentachlorocyclohexanols, but only resting cells of strain B90A could further transform the pentachlorocyclohexanol intermediates to the corresponding tetrachlorocyclohexanediols. Moreover, experiments with resting cells of Escherichia coli expressing the LinB proteins of strains B90A, UT26, and Sp؉ indicated that LinB was responsible for these transformations. Purified LinB proteins from all three strains also effected the formation of the respective pentachlorocyclohexanols. Although the three LinB enzymes differ only marginally with respect to amino acid sequence, they showed interesting differences with respect to substrate specificity. When LinB from strain B90A was incubated with ␤-and ␦-HCH, the pentachlorocyclohexanol products were further transformed and eventually disappeared from the incubation mixtures. In contrast, the LinB proteins from strains UT26 and Sp؉ could not catalyze transformation of the pentachlorocyclohexanols, and these products accumulated in the incubation mixture. A mutant of strain Sp؉ lacking linA and linB did not degrade any of the HCH isomers, including ␤-HCH, and complementation of this mutant by linB from strain B90A restored the ability to degrade ␤-and ␦-HCH.Hexachlorocyclohexane (HCH), a broad-spectrum insecticide, was one of the most extensively used organochlorine pesticides for the control of agricultural pests and the control of mosquitoes in malaria health programs during the 1940s. Technical HCH is prepared by chlorination of benzene in the presence of UV, resulting in the formation of a mixture primarily containing the isomers ␥-HCH (10 to 12%), ␣-HCH (60 to 70%), ␤-HCH (5 to 12%), and ␦-HCH (6 to 10%) (20). Of these isomers, only ␥-HCH (also known as lindane) has insecticidal properties. For purely economic reasons, technical HCH was used indiscriminately instead of lindane in many countries, and its use continued unabated until the 1990s, when the persistent and toxic nature of the components of technical mixtures was realized. Today, the use of technical HCH is banned in most countries, and the use of lindane is either banned or severely restricted. The extensive and widespread use, unregulated disposal, and persistent nature of HCH isomers have created the following two types of contamination problems: (i) low levels of contamination of agricultural soils and groundwater (3,14,25,32,39,45), mainly caused by the intended usage, and (ii) high levels of contamination at the production sites caused by inappropriate disposal of the noninsecticidal isomers ␣-, ␤-, and ␦-HCH. A large number of open or sealed dumping sites exist in The Netherlands (53), Brazil (36), Spain (24), Germany (13), India (39), and Eastern and Central Europe (53), which still pose serious risks for soils and groundwater.␣-and ␥-HC...

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Section: Discussionmentioning

confidence: 99%

Haloalkane Dehalogenase LinB Is Responsible for β- and δ-Hexachlorocyclohexane Transformation inSphingobium indicumB90A

Sharma

Raina

Kumari

et al. 2006

Appl Environ Microbiol

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“…Biodegradation of HCH isomers has been studied in soil [5], soil slurry [6] etc. A lot of information is available on the biodegradation of γ-HCH and other isomers of HCH using pure bacterial cultures, Pseudomonas aeruginosa, ITRC-5, Xanthomonas species, Clostridium rectum, Pandoraea spp etc [7][8][9][10]. Studies have also been carried out on the degradation of HCH isomers using sewage sludge under aerobic and anaerobic conditions [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Biodegradation of Hexachlorocyclohexane (HCH) Isomers by White Rot Fungus, Pleurotus florida

Mohapatra¹

2015

J Bioremed Biodeg

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Hexachlorocyclohexane (HCH) isomers are reported to persist in the environment long after their usage is discontinued. Pleurotus florida, a white rot fungus, was found to degrade not only γ-HCH but also its more persistent isomers individually as well as a mixture in a Raper's complete medium. Within 30 days γ-HCH degraded completely, whereas other 3 isomers degraded 92-99%. The degradation rate was γ-HCH>β-HCH>α-and δ-HCH. The mycelium biomass was free from γ-HCH residues but accumulated about 3% residues of other 3 isomers. Presence of intermediate metabolites was not detected indicating complete mineralization of HCH isomers. Ability of P. florida to degrade HCH isomers was further studied in soil by amendment with spent mushroom substrate (SMS). SMS addition could marginally increase degradation of α-, β-and δ-HCH, but significantly increased degradation of γ-HCH. When the study was repeated similar trend was observed. The half-life of degradation of γ-HCH was 439-570 days in un-amended soil while 37-42 days in SMS amended soil. For other 3 stable isomers the half-life was reduced from 686-828 to 88-125 days by SMS amendments. These results indicate that SMS from P. florida cultivation can be utilized for bioremediation of HCH contaminated site.

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“…Pseudomonas aeruginosa is also a soil organism that is ubiquitous throughout the environment and, like P. putida, is able to survive in many different chemically contaminated ecosystems (15,19,31,50). Unlike P. putida, it is an opportunistic pathogen, with an epidemic population structure, as clonal diversity is similar throughout different environments (32).…”

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confidence: 99%

Transcriptome Analysis Reveals that Multidrug Efflux Genes Are Upregulated To Protect Pseudomonas aeruginosa from Pentachlorophenol Stress

Muller¹,

Stevens²,

Craig

et al. 2007

Appl Environ Microbiol

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Through chemical contamination of natural environments, microbial communities are exposed to many different types of chemical stressors; however, research on whole-genome responses to this contaminant stress is limited. This study examined the transcriptome response of a common soil bacterium, Pseudomonas aeruginosa, to the common environmental contaminant pentachlorophenol (PCP). Cells were grown in chemostats at a low growth rate to obtain substrate-limited, steady-state, balanced-growth conditions. The PCP stress was administered as a continuous increase in concentration, and samples taken over time were examined for physiological function changes with whole-cell acetate uptake rates (WAURs) and cell viability and for gene expression changes by Affymetrix GeneChip technology and real-time reverse transcriptase PCR. Cell viability, measured by heterotrophic plate counts, showed a moderately steady decrease after exposure to the stressor, but WAURs did not change in response to PCP. In contrast to the physiological data, the microarray data showed significant changes in the expression of several genes. In particular, genes coding for multidrug efflux pumps, including MexAB-OprM, were strongly upregulated. The upregulation of these efflux pumps protected the cells from the potentially toxic effects of PCP, allowing the physiological whole-cell function to remain constant.

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Biodegradation of hexachlorocyclohexane-isomers in contaminated soils

Cited by 52 publications

References 38 publications

Haloalkane Dehalogenase LinB Is Responsible for β- and δ-Hexachlorocyclohexane Transformation inSphingobium indicumB90A

Haloalkane Dehalogenase LinB Is Responsible for β- and δ-Hexachlorocyclohexane Transformation inSphingobium indicumB90A

Biodegradation of Hexachlorocyclohexane (HCH) Isomers by White Rot Fungus, Pleurotus florida

Transcriptome Analysis Reveals that Multidrug Efflux Genes Are Upregulated To Protect Pseudomonas aeruginosa from Pentachlorophenol Stress

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