Isolation and Identification of Metribuzin Herbicide-Degrading Bacteria from Contaminated Cultivated Soils of Zanjan Province

The herbicide metribuzin is a triazine that remains in soil for long periods. It contaminates groundwater pollution and causes biological toxicity that causes concern worldwide. Microbial degradation plays a major role in removing triazine. This study was done to identify and isolate local bacteria for efficient degradation of metribuzin in the soils of Zanjan province. For this purpose, sampling of corn, apple and tomato fields from depths of 0 to 20 cm in spring was done. After preparation of soil samples and culture of them in the culture medium, the bacteria were purified. The synthetic growth of bacteria showed that ZT12, ZT15 and ZT19 isolates were from 21 isolates of bacteria with the increase of herbicide, the highest growth was observed at 500 mg/l, and the most significant isolate of ZT15 was detected by optical density of, 0.8629. It was, also determined that higher concentrations of 500 mg/L reduced growth of ZT15 isolate. Results of biochemical experiments and sequence investigation of bacterial isolates by interior primer indicate that bacterial strain ZT12, ZT15 and ZT19 are a strain of Enterobacter cancerogenus, Klebsiella sp. and Staphylococcus sp., respectively. Results of tests to determine presence or absence of metribuzin degrading gene or plasmid genomes of three bacteria isolates showed that the gene had been isolated on the plasmid. Cultivation of herbicide-degrading bacterial strains for release in a polluted environment is considered as appropriate for bioremediation.