Dibenzylsulfid (DBS) as a model of the organic sulfur compounds in crude oil was converted by a mixed culture (containing Pseudomonas aeruginosa) into several water soluble organic substances. Whereas these compounds are detectable with DC- and IR-spectroscopic techniques, benzylmercaptoacetic acid (BMA) was the only isolated product of DBS utilization. Efficiency of degradation, respectively, accumulation of BMA were dependent on aeration and pH-regulation.