Humic analog AQDS and AQS as an electron mediator can enhance chromate reduction by Bacillus sp. strain 3C3 |
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Authors: | Yiguo Hong Peng Wu Wenru Li Jiguang Gu Shunshan Duan |
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Institution: | (1) State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 Xingang Road West, Guangzhou, 510301, People’s Republic of China;(2) Institute of Hydrobiology, Jinan University, Guangzhou, 510632, People’s Republic of China;(3) Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangdong, 510070, People’s Republic of China |
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Abstract: | Humus as an electron mediator is recognized as an effective strategy to improve the biological transformation and degradation
of toxic substances, yet the action of humus in microbial detoxification of chromate is still unknown. In this study, a humus-reducing
strain 3C3 was isolated from mangrove sediment. Based on the analyses of morphology, physiobiochemical characteristics, and 16S rRNA
gene sequence, this strain was identified Bacillus sp. Strain 3C3 can effectively reduce humic analog anthraquinone-2,6-disulfonate (AQDS) and anthraquinone-2-sulfonate (AQS) with lactate,
formate, or glucose as electron donors. When the cells were killed by incubation at 95°C for 30 min or an electron donor was
absent, the humic reduction did not occur, showing that the humic reduction was a biochemical process. However, strain 3C3 had low capability of chromate reduction under anaerobic conditions, despite of having strong tolerance of the toxic metal.
But in the presence of humic substances AQDS or AQS, we found that chromate reduction by strain 3C3 was enhanced greatly. Because strain 3C3 is an effective humus-reducing bacterium, it is proposed that humic substances could serve as electron mediator to interact
with chromate and accelerate chromate reduction. Our results suggest that chromate contaminations can be detoxified by adding
humic analog (low to 0.1 mM) as an electron mediator in the microbial incubation. |
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