Inhibitory effects of 2-mercaptobenzothiazole on microbial growth in a variety of trophic conditions

2-Mercaptobenzothiazole (MET) is found mainly in the wastewaters of its industrial production as a rubber vulcanization accelerator. Because this compound was found to be toxic to activated sludges and because it causes poor process performances, its impact on bacteria in particular was studied. 2-Mercaptobenzothiazole, but not other benzothiazoles, exerted mainly bacteriostatic effects towards Escherichia coli, Sarcina lutea, Staphylococcus aureus, and a 2-hydroxybenzothiazole-degrading isolate (OBT18). It caused membrane disturbance as measured by induced potassium effluxes from the cell. Emphasis was on the effects of MBT on growth of E. coli on different electron donor-electron acceptor combinations. Paracoccus denitrificans was grown in the presence of oxygen or nitrate and the yeast Saccharomyces cerevisiae was used under aerobic and fermentative conditions. In almost all conditions the growth was severely inhibited, indicating that MBT might interfere with a common oxidoreduction step in membrane-bound systems and probably also interferes with metabolic reactions not related to the respiratory chain.