Isolation and characterization of a chlorate-reducing bacterium Ochrobactrum anthropi XM-1.

A Gram-negative chlorate-reducing bacterial strain XM-1 was isolated. The 16S rRNA gene sequence identified the isolate as Ochrobactrum anthropi XM-1, which was the first strain of genus Ochrobactrum reported having the ability to reduce chlorate. The optimum growth temperature and pH for strain XM-1 to reduce chlorate was found to be 30 °C and 5.0-7.5, respectively, under anaerobic condition. Strain XM-1 could tolerate high chlorate concentration (200 mM), and utilize a variety of carbohydrates (glucose, L-arabinose, D-fructose, sucrose), glycerin and sodium citrate as electron donors. In addition, oxygen and nitrate could be used as electron acceptors, but perchlorate could not be reduced. Enzyme activities related to chlorate reducing were characterized in cell extracts. Activities of chlorate reductase and chlorite dismutase could be detected in XM-1 cells grown under both aerobic and anaerobic conditions, implying the two enzymes were constitutively expressed. This work suggests a high potential of applying Ochrobactrum anthropi XM-1 for remediation of chlorate contamination.