ABSTRACT
Manganese-oxidizing microorganisms are able to oxidize soluble Mn(II) into insoluble Mn oxides. Such microorganisms are very useful in treatment of Mn-contaminated water. In this research, a Mn(II)- oxidizing bacterium Bacillus sp. MK3-1 was isolated from Mn-contaminated soil. This bacterium has high MnCl2 resistance with a MIC of 20 mmol/L. The results showed that it is able to oxidize and remove more than 96% of Mn(II) in the culture medium. The immobilized solid-embedding Bacillus sp. MK3-1can re- moved 87.12% of manganese contaminated water. The final concentration of MnCl2 after the treatment reached the national discharge standard level. Scan electron microscope observation showed that the pro- duced Mn oxides located on the cell surfaces of Bacillus sp. MK3-1. Energy dispersive spectrdmeter analy- sis indicated that the content of manganese of cell surfaces of Bacillus sp. MK3-1 was 19.60% (W/W). At last we amplified a 903 bp multicopper oxidase gene mnxG encoding the putative Mn(II)-oxidizing protein.The product of mnxG showed 86% identity to the reported multicopper oxidase.