Some Factors Affecting Degradation of Organochlorine Pesticides by Bacteria

Whole cells of Bacillus cereus, Bacillus coagulans, Bacillus subtilis, Escherichia colt and Enterobacter aerogenes in trypticase soy broth degraded DDT into two to eight metabolites. Seven metabolites were from aerobic growth of the Bacillus. Similar metabolites were from anaerobic growth of E. colt and E. aerogenes but less than four metabolites were from aerobic growth of these organisms. Metabolic pathway for the degradation of DDT was similar for the aforementioned species: DDT -> DDD -> DDMU -> DDMS -> DDNU -> (DDOH) -> DDA -> DBP or DDT -> DDE. Whole cells of Pseudomonas fluorescens and Staphylococcus aureus were unable to degrade DDT under aerobic conditions. None of the species was eapable of degrading DDT in skimmilk or in trypticase soy broth containing 3% whole casein. Degradation was greatly reduced in trypticase soy broth containing 4.5% lactose or individual fractions of alpha-, beta- and gamma-easein. None of the species degraded dieldrin and heptachlor.