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Start Over Author "Liu, Yanwei" Journal environmental science & technology
13 results on '"Liu, Yanwei"'

7. Superoxide-Mediated Extracellular Mercury Reduction by Aerobic Marine Bacterium Alteromonassp. KD01

Author

Zhang, Xiaoyan, Guo, Yingying, Liu, Guangliang, Liu, Yanwei, Shi, Jianbo, Hu, Ligang, Zhao, Lixia, Li, Yanbin, Yin, Yongguang, Cai, Yong, and Jiang, Guibin

Abstract

Microbial reduction plays a crucial role in Hg redox and the global cycle. Although intracellular Hg(II) reduction mediated by MerA protein is well documented, it is still unclear whether or how bacteria reduce Hg(II) extracellularly without its internalization. Herein, for the first time, we discovered the extracellular reduction of Hg(II) by a widely distributed aerobic marine bacterium Alteromonassp. KD01 through a superoxide-dependent mechanism. The generation of superoxide by Alteromonassp. KD01 was determined using 3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide and methyl cypridina luciferin analogue as probes via UV–vis and chemiluminescence detection, respectively. The results demonstrated that Hg(II) reduction was inhibited by superoxide scavengers (superoxide dismutase (SOD) and Cu(NO3)2) or inhibitors of reduced nicotinamide adenine dinucleotide (NADH) oxidoreductases. In contrast, the addition of NADH significantly improved superoxide generation and, in turn, Hg(II) reduction. Direct evidence of superoxide-mediated Hg(II) reduction was provided by the addition of superoxide using KO2in deionized water and seawater. Moreover, we observed that even superoxide at an environmental concentration of 9.6 ± 0.5 nM from Alteromonassp. KD01 (5.4 × 106cells mL–1) was capable of significantly reducing Hg(II). Our findings provide a greater understanding of Hg(II) reduction by superoxide from heterotrophic bacteria and eukaryotic phytoplankton in diverse aerobic environments, including surface water, sediment, and soil.

Published
2023
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