Isolation of hexachlorocyclohexane-degrading Sphingomonas sp. by dehalogenase assay and characterization of genes involved in γ-HCH degradation

• Published in: Journal of applied microbiology Vol. 104; no. 4; pp. 952 - 960
• Main Authors: Manickam, N, Reddy, M.K, Saini, H.S, Shanker, R
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01-04-2008; Blackwell Publishing Ltd; Blackwell Science
• Subjects: Base Sequence; Biodegradation, Environmental; Biological and medical sciences; Blotting, Southern - methods; Colorimetry; degradation; dehalogenase; Fundamental and applied biological sciences. Psychology; Gas Chromatography-Mass Spectrometry - methods; Genes, Bacterial; HCH; Hydrolases - analysis; lin genes; Lindane - metabolism; Microbiology; Molecular Sequence Data; RNA, Ribosomal, 16S - analysis; Soil Microbiology; Soil Pollutants - metabolism; Sphingomonas; Sphingomonas - enzymology; Sphingomonas - genetics; Sphingomonas - isolation & purification; Characterization; Degradation; lin genes; Gene; Applied microbiology; Bacteria; Isolation; Sphingomonas; dehalogenase; HCH
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/j.1365-2672.2007.03610.x

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. Dechlorinase activity assays were used to screen bacteria from contaminated soil samples for HCH-degrading activity. A bacterium able to grow on α-, β-, γ- and δ-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. γ-Pentachlorocyclohexene 1,2,4-trichlorobenzene and chlorohydroquinone were identified as metabolites. 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. 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.