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

The degradation characteristics of Tebuconazole degrading bacterium Serratia marcescens strain 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 Tebuconazole was 200 mg L−1, the degradation rate of Tebuconazole was 94.05% in 8 h. As the initial concentrations of Tebuconazole were higher than 300 mg L−1, the biodegradation rates declined as the Tebuconazole concentrations raised. As the concentration was 500 mg L−1, the Tebuconazole was degraded at a rate of only 64.11%. Degradation fit well with the kinetic equation of pesticide degradation as the initial concentrations of Tebuconazole were between 50 and 500 mg L−1. When strain B1 (cultured at 3 × 1014 CFU mL−1) was mixed with the soil contaminated with tebuconzole (200 mg L−1 and the concentration of strain B1 of 3 × 107 CFU g−1 dry soil), the Tebuconazole was 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 Tebuconazole in contaminated soil and Chinese cabbage.