[Isolation and characterization of a HCH degradation Sphingomanas sp. stain BHC-A].

An aerobic bacterium was isolated successfully from a long-term contaminated upland field, which was named BHC-A. The bacterium can utilize Hexachlorocycloexane as a sole carbon source and decompose this substance rapidly and completely. According to its physiological & biochemical characters and the homology analysis of its 16S rDNA sequence, this strain was identified as Sphingomonas sp. Stain BHC-A canmineralize not only alpha, gamma and delta-HCH rapidly, but also 5 mg/L beta-HCH in 12h completely. However, Sphingomonas paucimobilis UT26, a gamma-HCH-decomposing bacterium, can only degrade 12.6% of 5 mg/L alpha-HCH, but not beta-HCH and delta-HCH, even for more than 24h in the medium. The seedling of cucumber was selected as the model plant subject to the inhibition of HCH to the growth of cucurbitaceous plants. The results shows that the degradation of HCH isomers by BHC-A in soil is even steady and excellent, that BHC-A can eliminate the contamination of the soil and the harm to the plants.