Isolation and preliminary characterization of Bacillus sp. MCS, a gram-positive 4-chlorobiphenyl degrading bacterium

A mixed bacterial population was isolated from a garden soil inoculum after enrichment in a defined medium containing increasing amounts of 4-chlorobiphenyl (4-CB) as sole carbon source. The established population was composed of five bacteria from different genera, but only one, identified as belonging to the genus Bacillus and named MCS, had the ability to utilize 4-CB. In pure culture, the Bacillus isolate caused a reduction of 60% in the initial 4-CB concentration (200 mg litre−1) after 48 h of incubation and achieved total removal of the compound from the medium after seven days. Catabolite analysis provided evidence that Bacillus sp. MCS metabolizes 4-CB through a chain of reactions that ultimately generates 4-chlorobenzoic acid.