Biodegradation of beta-cypermethrin by two Serratia spp. with different cell surface hydrophobicity.

Serratia spp. strain JC1 and JCN13, isolated from activated sludge, could degrade and utilize beta-cypermethrin (beta-CP) as the sole carbon and energy sources for growth in the minimal salt media (MSM). The two strains could effectively degrade beta-CP with total inocula biomass 0.1-0.3g dry wtL(-1), at 20-38 degrees C, pH 6-9, initial beta-CP 25-1000mgL(-1) and metabolize it by cleavage of ester and diphenyl ether to yield 3-phenoxybenzoic acid (3-PBA) and phenol, then completely mineralize it. Response surface methodology (RSM) was used to optimize degradation conditions. Under their own optimal degradation conditions, strain JC1 could degrade 92% beta-CP within 10days and the degradation rate of strain JCN13 reached 89% within 4days. Cell surface hydrophobicity (CSH) and biodegradation assays indicated that JCN13 has higher hydrophobicity and degradation ability than JC1, and it means the high hydrophobicity of strains could enhance the degradation of beta-CP.