Enhancement of nitrite reduction and enrichment of Methylomonas via conductive materials in a nitrite-dependent anaerobic methane oxidation system.

Nitrite-dependent anaerobic methane-oxidizing (n-damo) process has a promising prospect in anaerobic wastewater treatment, utilizing methane as the sole electron source to remove nitrite. However, the metabolic activity of n-damo bacteria is too low for practical application. This study aimed to stimulate n-damo process by introducing conductive nano-magnetite and/or electron shuttle anthraquinone-2,6-disulfonate (AQDS), and also set a comparative treatment of adding insulated ferrihydrite. The results showed that the nitrite reduction rate was enhanced the most significantly in treatment with nano-magnetite, approximately 1.6 times higher than that of the control without any supplement. While ferrihydrite application showed an adverse effect on n-damo process. The well-known aerobic methane oxidizer Methylomonas spp. was found to be enriched under n-damo condition with the supplementation of nano-magnetite and/or AQDS, but abundance of n-damo bacteria did not exhibit significant increase. It was hypothesized that Methylomonas spp. could be survived under anaerobic n-damo condition using oxygen produced by n-damo bacteria for the self-growth, and the nitrite reduction could be promoted through the enhancement of microbial interspecies electron transfer triggered by the introduction of conductive materials. It opens a new direction for the stimulation of n-damo activity, which needs more evidences to verify the hypothetic mechanism. Copyright © 2020 Elsevier Inc. All rights reserved.

Citation

Jiali Chang, Qing Wu, Xiaoxu Yan, Han Wang, Liven Wenhui Lee, Yanchen Liu, Peng Liang, Yong Qiu, Xia Huang. Enhancement of nitrite reduction and enrichment of Methylomonas via conductive materials in a nitrite-dependent anaerobic methane oxidation system. Environmental research. 2021 Feb;193:110565

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PMID: 33275920

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