Isolation of hexachlorocyclohexane-degrading Sphingomonas sp. by dehalogenase assay and characterization of genes involved in gamma-HCH degradation.
OBJECTIVE
To screen and identify bacteria from contaminated soil samples which can degrade hexachlorocyclohexane (HCH)-isomers based on dechlorinase enzyme activity and characterize genes and metabolites.


RESULTS
Dechlorinase activity assays were used to screen bacteria from contaminated soil samples for HCH-degrading activity. A bacterium able to grow on alpha-, beta-, gamma- and delta-HCH as the sole carbon and energy source was identified. This bacterium was a novel species belonging to the Sphingomonas and harbour linABCDE genes similar to those found in other HCH degraders. Gamma-pentachlorocyclohexene 1,2,4-trichlorobenzene and chlorohydroquinone were identified as metabolites.


CONCLUSIONS
The study demonstrates that HCH-degrading bacteria can be identified from large environmental sample-based dehalogenase enzyme assay. This kind of screening is more advantageous compared to selective enrichment as it is specific and rapid and can be performed in a high-throughput manner to screen bacteria for chlorinated compounds.


CONCLUSIONS
The chlorinated pesticide HCH is a persistent and toxic environmental pollutant which needs to be remediated. Isolation of diverse bacterial species capable of degrading all the isomers of HCH will help in large-scale bioremediation in various parts of the world.
Environmental Biotechnology, Industrial Toxicology Research Centre, Mahatma Gandhi Marg, Lucknow, India. nmanickam2005@yahoo.com
N
N
Manickam
M K
MK
Reddy
H S
HS
Saini
R
R
Shanker
D001483:Base Sequence; D001673:Biodegradation, Environmental; D015139:Blotting, Southern / Q000379:methods; D003124:Colorimetry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D005798:Genes, Bacterial; D001556:Hexachlorocyclohexane / Q000378:metabolism*; D006867:Hydrolases / Q000032:analysis; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*; D020578:Sphingomonas / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*
D012336:RNA, Ribosomal, 16S; D012989:Soil Pollutants; D001556:Hexachlorocyclohexane; D006867:Hydrolases; C046137:haloalkane dehalogenase