Identification and characteristics of a moderate halotolerant nitrobenzene-degrading bacterium

Under high-salt(NaCl:1%) conditions,a strain named N18 with high degradation rate which utilized nitrobenzene as the sole source of carbon was domesticated and isolated from activated sludge of a pharmaceutical factory's aeration tank.According to its morphological,physiological and biochemical characteristics and analysis of both whole-cell fatty acid and 16S rRNA gene sequence,preliminary identification was made.The results showed that strain N18 was Bacillus cereus.The optimal growth and degradation condition of N18 were 10% inoculum,30℃ and pH 7.Additional glucose or sodium acetate accelerated the degradation rate from 72.70% to 82.62% and 79.25%,respectively(initial concentration of nitrobenzene was 200 mg · L-1 with degradation duration for 72h).Under the salinity of 1%~3%,the degradation rate of nitrobenzene basically unchanged.Even when the salinity(NaCl) was up to 10%,nitrobenzene was also degradable,which is classified as moderate halotolerant strain.When 150 mg · L-1 phenol or 75 mg · L-1 aniline was mixed into 200 mg · L-1 nitrobenzene,the degradation of the strain was still effective.The maximum tolerated concentration of Strain to nitrobenzene was 400 mg · L-1.