Isolation and characterization of a nitrobenzene degrading yeast strain from activated sludge.

Strain Z1 was isolated from nitrobenzene-contaminated sludge. Strain Z1 was able to utilize nitrobenzene as a sole source of carbon, nitrogen, and energy under aerobic condition. Based on the morphology, physiological biochemical characteristics, and 26S rDNA D1/D2 domain sequence, strain Z1 was identified as Rhodotorula mucilaginosa. Strain Z1 mineralized up to 450mg L(-1) nitrobenzene. Kinetics of nitrobenzene degradation was described using the Andrews equation. The kinetic parameters were as follows: q(max)=1.50h(-1), K(s)=31.31mg L(-1), and K(i)=101.34mg L(-1). Strain Z1 had a high-salinity tolerance. It degraded nitrobenzene effectively in 5% NaCl (quality concentration). Even in the presence of aniline or phenol, strain Z1 degraded nitrobenzene efficiently. Strain Z1 therefore could be an excellent candidate for the bio-treatment of nitrobenzene industrial wastewaters.