Enhancement of nitrite-dependent anaerobic methane oxidation via Geobacter sulfurreducens

Nitrite-dependent anaerobic methane-oxidation (n-damo) is a potential novel technology for nitrogen removal in anaerobic wastewater treatment. In this study, Geobacter sulfurreducens (G) was applied to stimulate n-damo activity. Conductive materials such as nano-magnetite (M) or aggregating agents such as hydroxylapatite (H) were co-added with G. sulfurreducens to further investigate the enhancement effect. Results showed that the nitrite reduction activity of the n-damo culture was promoted by G. sulfurreducens, with 1.71-2.38 times higher in treatment G, G M, and G + H than that in the control, but was inhibited by the single addition of hydroxylapatite. N-damo bacterial abundances based on the qPCR of the n-damo-specific pmoA gene increased in treatments with G. sulfurreducens, compared with that of the control. High-throughput sequencing analysis revealed the enrichment of uncultured phylum WPS-2 in treatments with G. sulfunvducens. Fluorescence in situ hybridization verified the co-occurrence pattern of n-damo bacteria (NC10), G. sulfurreducens, and type-I aerobic methanotrophs (Meihylomonas spp.). The above results corroborated the microbial interspecies electron transfer (MIET) potentiality of the n-damo enrichment. Our study provides a novel pathway for enhancing MIET to stimulate n-damo process. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the stimulation of nitrite-dependent anaerobic methane-oxidation (n-damo) activity by Geobacter sulfurreducens and the enhancement effect by adding nano-magnetite or hydroxylapatite. Results showed an increase in nitrite reduction activity and n-damo bacterial abundance in treatments with G. sulfurreducens. High-throughput sequencing analysis revealed the enrichment of uncultured phylum WPS-2 in these treatments, corroborating the microbial interspecies electron transfer potentiality of the n-damo enrichment.