[Manganese Oxidation Characteristics and Oxidation Mechanism of a Manganese-Oxidizing Bacterium Arthrobacter sp. HW-16]

Manganese is a common inorganic pollutant, which is difficult to remove from the environment. In this research, a high efficient manganese-oxidizing bacterium Arthrobacter sp. HW-16 was isolated from the manganese-rich soil using selective media. Besides, high-throughput sequencing revealed that there were significant differences of the microbial community compositions when bacteria were acclimated in different conditions, and Arthrobacte was the dominant genus in Mn(Ⅱ) containing media. In this paper, the microbiological properties of strain HW-16 and Mn(Ⅱ) oxidation mechanism were investigated. The results indicated that the maximal Mn(Ⅱ) tolerance mass concentration of strain HW-16 was 5000 mg·L^-1,and it exhibited a decent Mn(Ⅱ) oxidation efficiency with the highest value of 66.28% at a Mn(Ⅱ) concentration of 3000 mg·L^-1. Single factor experiments demonstrated that environmental factors could affect the growth and Mn(Ⅱ) oxidation efficiency of strain HW-16. At 30℃ or pH 7.0, at 1% or 3% salinity, and at 200 r·min^-1, strain HW-16 got the highest biomass. While the highest Mn(Ⅱ) oxidation efficiency occurred at high temperature (≥40℃), high pH (≥7), high shaking speed and low salinity. Strain HW-16 could oxidize Mn(Ⅱ) by producing Mn(Ⅱ) oxidizing active factor and turn Mn(Ⅱ) into precipitation by synthesizing alkaline metabolites.