论文部分内容阅读
Three bacterial strains (designated as BHC-B, BHC-C, and BHC-D) that degrade γ-hexachlorocyclohexane (γ-HCH) were isolated and characterized.They were all identified as Sphingobium sp.according to the phylogenetic analysis of the 16S rRNA gene sequence and the physiologic and biochemical characteristics.ERIC-PCR analysis was first used to determine the similarities of the different Sphingobium strains.Strains BHC-B, BHCC, and BHC-D could also degrade other three HCH isomers (α-, β-, and δ-isomer), and the degradation rates were in the following order of: γ-HCH > α-HCH > δ-HCH > β-HCH.For the same isomer, the degradation rates of the three HCH-degrading strains were in the following order: BHC-C > BHC-B > BHC-D.These three strains had six key lin genes (linA, linB, linC, linD, linE, linR).The sequence similarities of linA, linC, linD, linE, linR were 99% to 100% and highly conserved at the amino acid level.By contrast, the LinB sequence diverged by 2% to 3%, which might be responsible for the difference of the degradation rate in different strain against the same HCH isomer.However, further studies are needed to prove this hypothesis.