Effects of nutrients and environmental conditions on thiobencarb degradation by a mixed culture of Pseudomonas sp. Th1 and Cupriavidus oxalaticus Th2

Abstract

Thiobencarb is an herbicide component extensively applied for weed control. In this study, the mixed culture of Pseudomonas sp. Th1 and Cupriavidus oxalaticus Th2 was determined for degradability towards thiobencarb at several conditions. The degradation of thiobencarb at 50 µM by the mixture of these strains in the medium without any co-substrate was 48.5±5.5% for 24 hours, increased to 78.0% with the addition of 0.5 mg/L ammonium sulfate and 0.5 mg/L succinate in to the medium. Moreover, the mixed culture could degrade the compound at quite ranges of NaCl concentrations, pH and temperatures. To increase the degradation of the compound in a commercial herbicide, bacteria were immobilized in a matrix consisting of polyvinyl alcohol and sodium alginate. The average degradation of thiobencarb in an herbicide named Satunil 60E by immobilized bacteria was 25.8% higher than that of non-immobilized bacteria at a cell density of 1.0×107 CFUs/mL.

Keywords

• degradation
• herbicide
• immobilization
• thiobencarb