Degradation of 2-sec-butyl-4,6-dinitrophenol (dinoseb) by Clostridium bifermentans KMR-1

A strain of Clostridium bifermentans, KMR-1, degraded 2-sec-butyl-4,6-dinitrophenol (dinoseb) to a level below the limit of detection by high-performance liquid chromatography (0.5 mg/liter) within 96 h, with no accumulation of aromatic intermediates. KMR-1 could not utilize dinoseb as a sole carbon or energy source, and degradation occurred via cometabolism in the presence of a fermentable carbon source. KMR-1 mineralized some dinoseb in anaerobic cultures, evolving 7.2% of the radioactive label in U-ring 14C-labeled dinoseb as 14CO2. The remaining anaerobic degradation products were incubated with aerobic soil bacteria, and 35.4% of this residual radioactive label was evolved as 14CO2. During this mineralization experiment, 38.9% of the initial label was evolved as 14CO2 after both anaerobic and aerobic phases. This is the first demonstration of dinoseb degradation by a pure microbial culture.