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Detoxification of 1,1,2-trichloroethane to ethene by desulfitobacterium and identification of its functional reductase gene.

Zhao S, Ding C, He J - PLoS ONE (2015)

Bottom Line: Later, through transcriptomic and enzymatic analysis, the reductive dehalogenase CtrA, which was previously reported to be responsible for 1,1,1-trichloroethane and chloroform dechlorination, was identified as the 1,1,2-TCA reductive dehalogenase.Interestingly, this co-culture dechlorinated 1,1,2-TCA and TCE to the non-toxic end-product ethene within 48 days without chloroethane production.This novel pathway avoids production of the carcinogenic intermediate dechlorination product vinyl chloride, providing a more environmentally friendly strategy to treat 1,1,2-TCA.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore.

ABSTRACT
1,1,2-trichloroethane (1,1,2-TCA) has become a common groundwater pollutant due to historically extensive utilization, improper disposal, as well as from incomplete dechlorination of 1,1,2,2-tetrachloroethane. Currently, limited information is available on microbial detoxification of 1,1,2-TCA. Desulfitobacterium sp. strain PR, which was isolated from an anaerobic bioreactor maintained to dechlorinate chloroethenes/ethanes, exhibited the capacity to dechlorinate 1,1,1-trichloroethane and chloroform. In this study, the dechlorinating ability of strain PR was further explored. Strain PR showed the capability to dechlorinate 1,1,2-TCA (~1.12 mM) predominantly to 1,2-dichloroethane (1,2-DCA) and chloroethane, and to trace amounts of vinyl chloride and ethene within 20 days. Strain PR coupled growth with dechlorination of 1,1,2-TCA to 1,2-DCA, while no cell growth was observed with dechlorination of 1,2-DCA to chloroethane. Later, through transcriptomic and enzymatic analysis, the reductive dehalogenase CtrA, which was previously reported to be responsible for 1,1,1-trichloroethane and chloroform dechlorination, was identified as the 1,1,2-TCA reductive dehalogenase. Since trichloroethene (TCE) is usually co-contaminated with 1,1,2-TCA, a co-culture containing Dehalococcoides mccartyi strain 11a capable of detoxifying TCE and 1,2-DCA and strain PR was established. Interestingly, this co-culture dechlorinated 1,1,2-TCA and TCE to the non-toxic end-product ethene within 48 days without chloroethane production. This novel pathway avoids production of the carcinogenic intermediate dechlorination product vinyl chloride, providing a more environmentally friendly strategy to treat 1,1,2-TCA.

No MeSH data available.


Related in: MedlinePlus

Dechlorination of 1,1,2-TCA by a co-culture consisting of strain PR and a mixed culture GEO.Note: CA, chloroethane; VC, vinyl chloride; ETH, ethene.
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pone.0119507.g005: Dechlorination of 1,1,2-TCA by a co-culture consisting of strain PR and a mixed culture GEO.Note: CA, chloroethane; VC, vinyl chloride; ETH, ethene.

Mentions: In order to achieve complete dechlorination of 1,1,2-TCA, a co-culture was established with strain PR and a highly enriched mixed culture, GEO, that is capable of dechlorinating 1,2-DCA to ethene via dihaloelimination. When 1,1,2-TCA (~ 0.62 mM) was spiked into the medium, this co-culture sequentially dechlorinated 1,1,2-TCA to 1,2-DCA and chloroethane on day 11 (Fig. 5). Most of the 1,2-DCA produced was rapidly dechlorinated to ethene, however, a fraction of 1,2-DCA was still dechlorinated to chloroethane co-metabolically by strain PR. By day 25, all of the 1,1,2-TCA had been converted to chloroethane (~ 0.35 mM) and ethene (~ 0.26 mM).


Detoxification of 1,1,2-trichloroethane to ethene by desulfitobacterium and identification of its functional reductase gene.

Zhao S, Ding C, He J - PLoS ONE (2015)

Dechlorination of 1,1,2-TCA by a co-culture consisting of strain PR and a mixed culture GEO.Note: CA, chloroethane; VC, vinyl chloride; ETH, ethene.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383557&req=5

pone.0119507.g005: Dechlorination of 1,1,2-TCA by a co-culture consisting of strain PR and a mixed culture GEO.Note: CA, chloroethane; VC, vinyl chloride; ETH, ethene.
Mentions: In order to achieve complete dechlorination of 1,1,2-TCA, a co-culture was established with strain PR and a highly enriched mixed culture, GEO, that is capable of dechlorinating 1,2-DCA to ethene via dihaloelimination. When 1,1,2-TCA (~ 0.62 mM) was spiked into the medium, this co-culture sequentially dechlorinated 1,1,2-TCA to 1,2-DCA and chloroethane on day 11 (Fig. 5). Most of the 1,2-DCA produced was rapidly dechlorinated to ethene, however, a fraction of 1,2-DCA was still dechlorinated to chloroethane co-metabolically by strain PR. By day 25, all of the 1,1,2-TCA had been converted to chloroethane (~ 0.35 mM) and ethene (~ 0.26 mM).

Bottom Line: Later, through transcriptomic and enzymatic analysis, the reductive dehalogenase CtrA, which was previously reported to be responsible for 1,1,1-trichloroethane and chloroform dechlorination, was identified as the 1,1,2-TCA reductive dehalogenase.Interestingly, this co-culture dechlorinated 1,1,2-TCA and TCE to the non-toxic end-product ethene within 48 days without chloroethane production.This novel pathway avoids production of the carcinogenic intermediate dechlorination product vinyl chloride, providing a more environmentally friendly strategy to treat 1,1,2-TCA.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore.

ABSTRACT
1,1,2-trichloroethane (1,1,2-TCA) has become a common groundwater pollutant due to historically extensive utilization, improper disposal, as well as from incomplete dechlorination of 1,1,2,2-tetrachloroethane. Currently, limited information is available on microbial detoxification of 1,1,2-TCA. Desulfitobacterium sp. strain PR, which was isolated from an anaerobic bioreactor maintained to dechlorinate chloroethenes/ethanes, exhibited the capacity to dechlorinate 1,1,1-trichloroethane and chloroform. In this study, the dechlorinating ability of strain PR was further explored. Strain PR showed the capability to dechlorinate 1,1,2-TCA (~1.12 mM) predominantly to 1,2-dichloroethane (1,2-DCA) and chloroethane, and to trace amounts of vinyl chloride and ethene within 20 days. Strain PR coupled growth with dechlorination of 1,1,2-TCA to 1,2-DCA, while no cell growth was observed with dechlorination of 1,2-DCA to chloroethane. Later, through transcriptomic and enzymatic analysis, the reductive dehalogenase CtrA, which was previously reported to be responsible for 1,1,1-trichloroethane and chloroform dechlorination, was identified as the 1,1,2-TCA reductive dehalogenase. Since trichloroethene (TCE) is usually co-contaminated with 1,1,2-TCA, a co-culture containing Dehalococcoides mccartyi strain 11a capable of detoxifying TCE and 1,2-DCA and strain PR was established. Interestingly, this co-culture dechlorinated 1,1,2-TCA and TCE to the non-toxic end-product ethene within 48 days without chloroethane production. This novel pathway avoids production of the carcinogenic intermediate dechlorination product vinyl chloride, providing a more environmentally friendly strategy to treat 1,1,2-TCA.

No MeSH data available.


Related in: MedlinePlus