Evaluation of sulfate-reducing bacteria for desulfurizing bitumen or its fractions

Type cultures of sulfate-reducing bacteria (SRB), SRB obtained from oilfield production facilities and a sulfate-reducing microbial community obtained from Athabasca oil sands (ANFI) were examined for their ability to desulfurize bitumen or its associated fractions. No significant reduction of the sulfur content of dibenzothiophene (DBT) was observed for Desulfovibrio vulgaris or ANFI, even though these cultures convert maximally 1% of DBT into biphenyl (BP), as found previously. Furthermore, no significant reduction was observed in total sulfur content of vacuum gas oil, deasphalted oil or bitumen with this method. Growth of Desulfovibrio vulgaris or ANFI in the presence of DBT, bitumen or its fractions in medium lacking methylviologen also did not lead to significant reduction in their total sulfur contents, even though the ANFI community appeared able to utilize the real feeds as a potential carbon and energy source. (C) 1997 Elsevier Science Ltd.