Microbial transformations of 2-substituted benzothiazoles.

Area of Science:

• Environmental chemistry
• Microbiology
• Environmental science

Background:

• Benzothiazoles are environmental contaminants primarily found in aquatic systems.
• Their presence is linked to the use of 2-mercaptobenzothiazole (MBT) and its derivatives as rubber additives.
• Limited data exists on benzothiazole biotransformation at low environmental concentrations (ppb and ppt).

Purpose of the Study:

• To review the environmental occurrence and biotransformation of benzothiazoles.
• To assess the biodegradability of various benzothiazole compounds.
• To identify factors affecting their fate in the environment, including inhibitory effects on biological treatment.

Main Methods:

• Literature review of environmental occurrence and biodegradation studies.
• Analysis of data on benzothiazole biotransformation pathways.
• Evaluation of factors influencing degradation, such as concentration and microbial activity.

Main Results:

• Unsubstituted benzothiazole (BT) and 2-hydroxybenzothiazole (OBT) are generally biodegradable.
• 2-methylthiobenzothiazole is recalcitrant, and 2-thiocyanomethylthiobenzothiazole likely hydrolyzes to MBT.
• BT and MBT can inhibit biological treatment processes above certain threshold concentrations.
• Biodegradation of BT, MBT, 2-aminobenzothiazole, and benzothiazole-2-sulphonate can occur, but may produce byproducts.

Conclusions:

• Benzothiazole biodegradability varies among compounds, with some being persistent.
• High concentrations of BT and MBT can negatively impact wastewater treatment efficiency.
• Further research is needed to fully elucidate benzothiazole degradation pathways due to limited axenic cultures.