The microbial degradation of benzothiazoles

The biodegradation of benzothiazoles by pure and mixed microbial cultures derived from activated sludge has been studied. The degradation of 2-aminobenzothiazole (ABT) by both pure and mixed bacterial cultures has been demonstrated for the first time. ABT is degraded to give high yields of ammonia and sulphate (87 and 100 %, respectively of the theoretical yield). We also report for the first time the isolation of a pure bacterial culture PA, thought to be a strain of Rhodococcus , capable of growing on benzothiazole (BTH) itself as a sole carbon, nitrogen and energy source. Evidence is presented to suggest that this organism degrades BTH via the meta-cleavage pathway. The Rhodococcus PA degrades BTH but only releases a small proportion (5%) of the sulphur as sulphate. Mixed cultures containing this organism released ca 100% of the sulphur as sulphate, suggesting that other members of the consortium catalyse conversion of a sulphur-containing intermediate to sulphate. 2-Mercaptobenzothiazole (MBT) could not act as a growth substrate for any of the cultures studied but some could cause biotransformation of MBT to some extent. Attempts to obtain cultures degrading ABT and BTH from polluted river water were unsuccessful.