Metagenomics uncovers the effect of nitrogen-doped graphene on anammox consortia and microbial function

The effect of 50 mg/L nitrogen-doped graphene (N-G) on anammox microbial guild was studied by metagenomics in this paper. The continuous experiment results showed the average NRE improved by 17.57% with N-G addition. The metagenomic analysis revealed N-G significantly increased the relative abundance of dominant AnAOB (Candidatus Kuenenia) from 18.10% to 28.30%. And the FISH assay further manifested N-G promoted the growth of AnAOB biomass. Meanwhile, metagenomics indicated that N-G enriched the abundance of genes (Hzs, Hdh, NosZ, NorB, NirK, NirS and NrfA) involved in nitrogen metabolism to varying degrees. Furthermore, N-G not only improved the microbial functionality in terms of Metabolism, but markedly upregulated the abundance of c-di-GMP synthesized genes and genes related to quinolone signal molecule, which contributed to more EPS content and better sludge settleability. In brief, this study provided a novel perspective for anammox biomass enrichment, which may be valuable for practical engineering applications of anammox.

Automated summary

This study investigated the effect of nitrogen-doped graphene (N-G) on anammox microbial guild through metagenomics. The results showed that adding N-G significantly improved the nitrogen removal efficiency and promoted the growth of dominant anammox bacteria. Metagenomic analysis revealed that N-G enriched the abundance of genes involved in nitrogen metabolism and also upregulated genes related to microbial functionality and sludge settleability. This study provides a novel perspective for the enrichment of anammox biomass and has practical implications for anammox engineering applications.