Enhanced degradation of hexachlorocyclohexane isomers by Sphingomonas paucimobilis

Hexachlorocyclohexane (HCH) has been banned for use in technologically adva nced countries; however, it is still in use in tropical countries like Indi a. Earlier we reported the degradation of HCH isomers by Sphingomonas pauci mobilis within 12 days of incubation. Here we report the role of different factors that could enhance the degradation rate of HCH isomers. We found th at an increase in the cell number from 10(2) to 10(8) cells/ml resulted in an increased degradation rate of HCH isomers viz, alpha, beta, gamma, and d elta -HCH. While alpha -HCH and gamma -HCH disappeared completely from the medium within 3 days of incubation, a maximum of only 90% and 85% degradati on was observed for beta and delta -HCH, respectively. We have also observe d that adapted cultures degraded HCH isomers more efficiently than did the normal cultures.