Composition of bacterial community and isolation of bacteria responsible for diuron degradation in sediment and soil under anaerobic condition

Abstract

The herbicide diuron is extensively used in the agriculture sector and is detected widely in the environment. Although several studies on the degradation of diuron by aerobic micro-organisms have been reported, the degradation of diuron by anaerobic micro-organisms has not been received much attention. Also, no pure culture that can degrade diuron under anaerobic conditions has yet been reported. The evaluation of diuron degradation in the soil and sediment slurries showed that diuron led to a decrease in the biodiversity of the bacterial communities. Two mixed bacterial cultures, one from the soil and the other from sediment slurries, were isolated from the enrichment media under anaerobic conditions. After 30 days of incubation at 30 oC, the mixed bacterial culture from the soil degraded 84.5 ± 5.5%, and that from the sediment slurry degraded 94.5 ± 3.0% of diuron in liquid mineral medium at an initial concentration of 20 mg/L. 1-(3,4-dichlorophenylurea (DCPU), 3-(3-chlorophenyl)-1,1-dimethylurea (CPDMU), and 3,4-dichloroaniline (3,4-DCA) were the major diuron metabolites produced by both the indigenous micro-organisms and the isolated bacteria.