Biodegradation of beta-cypermethrin and 3-phenoxybenzoic acid by a novel Ochrobactrum lupini DG-S-01

A newly isolated bacterium DG-S-01 from activated sludge utilized beta-cypermethrin (beta-CP) and its major metabolite 3-phenoxybenzoic acid (3-PBA) as sole carbon and energy source for growth in mineral salt medium (MSM). Based on the morphology, physio-biochemical characteristics, and 16S rDNA sequence analysis, DG-S-01 was identified as Ochrobactrum lupini. DG-S-01 effectively degraded beta-CP with total inocula biomass A(590) nm = 0.1-0.8, at 20-40 degrees C, pH 5-9, initial beta-CP 50-400 mg L-1 and metabolized to yield 3-PBA leading to complete degradation. Andrews equation was used to describe the special degradation rate at different initial concentrations. Degradation rate parameters q(max). K-s and K-i were determined to be 1.14 d(-1), 52.06 mg L-1 and 142.80 mg L-1, respectively. Maximum degradation was observed at 30 degrees C and pH 7.0. Degradation of beta-CP was accelerated when MSM was supplemented with glcose, beef extract and yeast extract. Studies on biodegradation in liquid medium showed that over 9C% of the initial dose of beta-CP (SO mg L-1) was degraded under the optimal conditions within 5d. Moreover, the strain also degraded beta-cyfluthrin, fenpropathrin, cyhalothrin and deltamethrin. These results reveal that DG-S-01 may possess potential to be used in bioremediation of pyrethroid-contaminated environment. (C) 2011 Elsevier B.V. All rights reserved.