Genetic manipulations of microorganisms for the degradation of hexachlorocyclohexane

Johri, A

doi:10.1016/s0168-6445(96)00024-1

Cited by 9 publications

(11 citation statements)

References 61 publications

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“…However, in some areas in the world, this insecticide is still in use for economic reasons and thus, new areas continue to be contaminated. Theoretically, HCH has eight possible stereoisomers, of which four (α‐, β‐, γ‐ and δ‐HCH) predominate in the commercial products (Johri et al ., 1996). γ‐HCH is the best‐known and effective insecticide component of HCH, and only 9–18% of commercial HCH consists of this γ‐isomer.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the role of LinA and LinB in biodegradation of δ‐hexachlorocyclohexane

Jun

Hong

Sun

et al. 2007

Environmental Microbiology

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Commercial formulations of hexachlorocyclohexane (HCH) consist of a mixture of four isomers, alpha, beta, gamma and delta. All these four isomers are toxic and recalcitrant pollutants. Sphingobium (formerly Sphingomonas) sp. strain BHC-A is able to degrade all four HCH isomers. Eight lin genes responsible for the degradation of gamma-HCH in BHC-A were cloned and analysed for their role in the degradation of delta-HCH, and the initial conversion steps in delta-HCH catabolism by LinA and LinB in BHC-A were found. LinA dehydrochlorinated delta-HCH to produce 1,3,4,6-tetrachloro-1,4-cyclohexadiene (1,4-TCDN) via delta-pentachlorocyclohexene (delta-PCCH). Subsequently, both 1,4-TCDN and delta-PCCH are catalysed by LinB via two successive rounds of hydrolytic dechlorinations to form 2,5-dichloro-2,5-cyclohexadiene-1,4-diol (2,5-DDOL) and 2,3,5-trichloro-5-cyclohexene-1,4-diol (2,3,5-TCDL) respectively. LinB could also catalyse the hydrolytic dechlorination of delta-HCH to 2,3,5,6-tetrachloro-1,4-cyclohexanediol (TDOL) via 2,3,4,5,6-pentachlorocyclohexanol (PCHL).

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Section: Introductionmentioning

confidence: 99%

Analysis of the role of LinA and LinB in biodegradation of δ‐hexachlorocyclohexane

Jun

Hong

Sun

et al. 2007

Environmental Microbiology

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“…One possibility for decontamination is spontaneous or induced microbial degradation. Unfortunately, spontaneous microbial degradation of HCH isomers proceeds rather slowly (10,15), although a number of bacteria which can degrade one or more isomers of HCH have been isolated. Thus, addition of naturally occurring microbes to contaminated soils could provide an alternative strategy.…”

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confidence: 99%

“…These three strains are remarkably similar and can all degrade ␣-, ␥-, and ␦-HCH (9,14,29,37). In addition, S. paucimobilis B90A can also partially degrade ␤-HCH (10,14,29). The metabolic pathway and the genes involved in HCH degradation have been studied in great detail in S. paucimobilis strain UT26 (a mutant of SS86 resistant to nalidixic acid) and to a lesser extent in B90 (Fig.…”

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Organization of lin Genes and IS 6100 among Different Strains of Hexachlorocyclohexane-Degrading Sphingomonas paucimobilis : Evidence for Horizontal Gene Transfer

et al. 2004

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The organization of lin genes and IS6100 was studied in three strains of Sphingomonas paucimobilis (B90A, Sp؉, and UT26) which degraded hexachlorocyclohexane (HCH) isomers but which had been isolated at different geographical locations. DNA-DNA hybridization data revealed that most of the lin genes in these strains were associated with IS6100, an insertion sequence classified in the IS6 family and initially found in Mycobacterium fortuitum. Eleven, six, and five copies of IS6100 were detected in B90A, Sp؉, and UT26, respectively. IS6100 elements in B90A were sequenced from five, one, and one regions of the genomes of B90A, Sp؉, and UT26, respectively, and were found to be identical. DNA-DNA hybridization and DNA sequencing of cosmid clones also revealed that S. paucimobilis B90A contains three and two copies of linX and linA, respectively, compared to only one copy of these genes in strains Sp؉ and UT26. Although the copy number and the sequence of the remaining genes of the HCH degradative pathway (linB, linC, linD, and linE) were nearly the same in all strains, there were striking differences in the organization of the linA genes as a result of replacement of portions of DNA sequences by IS6100, which gave them a strange mosaic configuration. Spontaneous deletion of linD and linE from B90A and of linA from Sp؉ occurred and was associated either with deletion of a copy of IS6100 or changes in IS6100 profiles. The evidence gathered in this study, coupled with the observation that the G؉C contents of the linA genes are lower than that of the remaining DNA sequence of S. paucimobilis, strongly suggests that all these strains acquired the linA gene through horizontal gene transfer mediated by IS6100. The association of IS6100 with the rest of the lin genes further suggests that IS6100 played a role in shaping the current lin gene organization.Hexachlorocyclohexane (HCH) was introduced for the control of agricultural pests and of vector-borne diseases in early 1940s. While this compound was used extensively all over the world, several reports on the persistence of HCH isomers (␣, ␤, ␥, and ␦) and their toxic effects on nontarget organisms appeared in the 1980s (11). These reports finally resulted in a ban on or restricted use of HCH in most countries. Neither the ban nor the restricted use has, however, reduced the levels of HCH residues in the environment (6, 25, 33), especially in soils that had a previous history of HCH application (2). One serious problem is the uptake of HCH residues from soil by crops, which then enter food products (1, 31). In addition to no further use of HCH, a decontamination program for HCHpolluted soils would diminish the risk posed by HCH residues to human, plant, and animal health. One possibility for decontamination is spontaneous or induced microbial degradation. Unfortunately, spontaneous microbial degradation of HCH isomers proceeds rather slowly (10, 15), although a number of bacteria which can degrade one or more isomers of HCH have been isolated. Thus, addition of naturally occu...

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“…Two bacterial strains (Sphingomonas paucimobilis UT26 and S. paucimobilis B90A) which are able to degrade ␥-HCH also degrade ␣-HCH (6,8,20). Likewise, purified LinA from S. paucimobilis UT26, a dehydrochlorinase catalyzing the first step in the degradation pathway of ␥-HCH, dehydrochlorinates not only ␥-HCH but also ␣-HCH, ␦-HCH, ␥-pentachlorocyclohexene (␥-PCCH), and ␣-PCCH, whereas ␤-HCH is not dehydrochlorinated (18).…”

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confidence: 99%

Enantioselective Transformation of α-Hexachlorocyclohexane by the Dehydrochlorinases LinA1 and LinA2 from the Soil Bacterium Sphingomonas paucimobilis B90A

Suar

Hauser²,

Poiger³

et al. 2005

Appl Environ Microbiol

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Genetic manipulations of microorganisms for the degradation of hexachlorocyclohexane

Cited by 9 publications

References 61 publications

Analysis of the role of LinA and LinB in biodegradation of δ‐hexachlorocyclohexane

Analysis of the role of LinA and LinB in biodegradation of δ‐hexachlorocyclohexane

Organization of lin Genes and IS 6100 among Different Strains of Hexachlorocyclohexane-Degrading Sphingomonas paucimobilis : Evidence for Horizontal Gene Transfer

Enantioselective Transformation of α-Hexachlorocyclohexane by the Dehydrochlorinases LinA1 and LinA2 from the Soil Bacterium Sphingomonas paucimobilis B90A

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