Aerobic degradation of pyridine by a new bacterial strain, Shinella zoogloeoides BC026

Abstract

A new bacterial strain, Shinella zoogloeoides BC026, which utilizes pyridine as its sole carbon, nitrogen and energy source, was isolated from the activated sludge of a coking wastewater treatment plant. The BC026 strain completely degraded up to 1,806 mg/l of pyridine in 45.5 h. The optimum degradation conditions were pH 8.0 and temperature 30-35 degrees C. According to product monitoring and genetic analysis, the pyridine ring was cleaved between C(2) and N, resulting in 58% of pyridine-N being directly converted into ammonium. Providing glucose as the extra carbon source, the degradation of pyridine was not affected, while the growth of the strain was promoted, and 41% of pyridine-N was converted into ammonium with a C/N ratio of 35. The ammonium was utilized rapidly by the strain, and a portion of it was transformed into nitrate, then to nitrite, and finally to dinitrogen if enough extra carbon was provided. Considering these characteristics, this strain may accomplish heterotrophic nitrification and aerobic denitrification simultaneously.