Identification and characterization of a cold-adapted and halotolerant nitrobenzene-degrading bacterium

Abstract

A strain named X7, which uses nitrobenzene (NB) as a carbon source at low temperature and high salinity, was domesticated and isolated from activated sludge in the aeration tank of Shenyang Northern Sewage Treatment Plant. According to its morphological, physiological and biochemical characteristics and 16S rDNA gene sequence, a preliminary identification was made. The result showed that strain X7 was Myroides odoratus. The optimal degradation conditions of strain X7 were as follows: inoculum concentration 10%, optimal temperature 15 °C, pH 7.0, rotary speed 150 rpm and salinity 1.0%–3.0%. At an initial concentration of nitrobenzene of 150 mg L⁻¹, the degradation rate was 51.50%. Moreover, the addition of glucose and peptone could increase the degradation rate to 58.92% and 60.24%, respectively. The maximum concentration of nitrobenzene that was tolerated by strain X7 was 350 mg L⁻¹.