Manganese Removal Mechanisms of Five Bacterial Strains with the Abilities to Produce MnCO3

Abstract:

Five manganese-resistant and manganese-removing bacterial strains were isolated from soil samples of a Zn-Mn mine in Hunan and manganese storage of Xi Qingma steel factory in Tianjin and named as J2-3, J4-3, J12-1, JM3-2 and JD. Based on morphological, physiological/biochemical tests and 16S rRNA gene analysis, these strains were identified as Hydrogenophaga, Mycobacterium, Rhodococcus, Acinetobacter and Bacillus respectively. The minimal inhibitory concentration (MIC) of JM3-2 and JD were 2 mmol/L while MIC of J2-3, J4-3, and J12-1 reached 12 mmol/L. The X-ray diffraction analysis showed that the precipitate formed by the Mn(Ⅱ)-removal bacteria was MnCO3. All of the 5 strains could remove manganese effectively ( > 85%). Strains JD and JM3-2 removed 94.28% ± 0.1% and 93.10% ± 3.1% Mn(Ⅱ) from the medium, respectively. During the removing process, the pH increased from 7.0 to more than 8.5. This indicated the mechanism of manganese removing may caused by the metabolism of the Mn(Ⅱ)-removing bacteria to transform of soluble Mn(Ⅱ) into the insoluble MnCO3 when pH increased. Here we report a new-type of manganese-removing bacteria, which is different from the maganese-oxidizing bacteria reported before.