Biodegradation and toxicity of benzothiazoles

Benzothiazoles appear in the environment mainly as a result of their production and use as rubber vulcanization accelerators. This review focuses on the potential environmental hazard these substances pose and their biological removal from and transformation in aquatic and terrestrial ecosystems. Benzothiazole degradation by mixed and pure cultures and the toxic impact on microorganisms are discussed. It is concluded that biological purification of wastewaters from 2-mercaptobenzothiazole (MBT) production can be achieved, provided the MBT influent concentration is 100 mg/l at maximum. So far, no attempts have been made to study the molecular mechanisms of benzothiazole degradation, mainly due to the unavailability of axenic cultures capable of benzothiazole breakdown. However, the toxic effects of MBT towards microorganisms have been studied and can be attributed to its metal chelating properties and/or its interference with membrane-bound (co)enzymes in particular.