Biodegradation of fungicide Tebuconazole by Serratia marcescens strain B1 and its application in bioremediation of contaminated soil

Abstract The degradation characteristics of Tebuconazoledegrading bacterium Serratia marcescensstrain B1 in both contaminated soil and culture were investigated in this study. In the liquid mineral salt medium, the optimal temperature, pH value, and inoculation (v/v) for degradation by strain B1 were 30 °C, 7.0, and 4.0%, respectively. When the initial concentration of Tebuconazolewas 200 mg L −1 , the degradation rate of Tebuconazolewas 94.05% in 8 h. As the initial concentrations of Tebuconazolewere higher than 300 mg L −1 , the biodegradation rates declined as the Tebuconazoleconcentrations raised. As the concentration was 500 mg L −1 , the Tebuconazolewas degraded at a rate of only 64.11%. Degradation fit well with the kinetic equation of pesticide degradationas the initial concentrations of Tebuconazolewere between 50 and 500 mg L −1 . When strain B1 (cultured at 3 × 10 14 CFU mL −1 ) was mixed with the soil contaminatedwith tebuconzole (200 mg L −1 and the concentration of strain B1 of 3 × 10 7 CFU g −1 dry soil), the Tebuconazolewas degraded at a rate of 96.46% in 30 days, while the control soil (with the absence of strain B1) achieved a degradation rate of only 70.42%. These results demonstrate that in contaminated soil, the strain B1 can substantially increase the degradation rate of Tebuconazole. Results of the greenhouse and field experiments indicate that the strain B1 can remove the residues of Tebuconazolein contaminated soil and Chinese cabbage.