[Isolation, molecular characterization and resistance mechanism study on a cadmium hyperresistant Bacillus cereus]

A Gram-positive, aerobic, motile, spore-forming bacterium was isolated from a Pb-Zn mine tailing at suburb of Beijing City. The bacterial strain isolated could resist cadmium efficiently and it was able to grow well on media plates containing 1 000 mg/L cadmium. The DNA G + C content were found to be 60%. Phylogenetic analysis of the 16S rRNA gene revealed that this isolate was a member of the genus Bacillus. Two growth curves about this strain were drawn on media with and without cadmium. This strain harbors a plasmid putatively bearing essential cadmium resistant genes as demonstrated by a plasmid elimination experiment. The results of this study indicate that this strain has a better potential for cadmium resistance compared to other reports. The physiological characterization of the isolates also indicates the possible application of this strain for bioremediation of sites contaminated with cadmium.