Metagenomic insights into functional traits variation and coupling effects on the anammox community during reactor start-up

Abstract

Anammox technology is an energy-efficient wastewater treatment process and anammox community structure has gained extensive attention. However, the dynamics of community functional traits are still elusive. Here, we combined the long-term reactor operation and metagenomic, multiple bioinformatic and network analyses to reveal the succession of anammox community and function traits during reactor start-up. We found the cooperation of denitrifiers that affiliated to the phylum Proteobacteria could reduce nitrite to dinitrogen gas. These organisms and genes had higher abundance after the inhibition phase, which could contribute to nitrite consuming and reactor performance recovery. Importantly, the Terrimonas and Anaerolinea organisms had ability of extracellular polymers secretion or aggregate formation. They had the highest abundance at the end of the lag phase, which could benefit for promoting the nitrogen removal rate (NRR). Meanwhile, Terrimonas and Anaerolinea bacteria could cooperate with methanogenic and nitrite-denitrifying methanotrophic organisms based on H2 and CH4, respectively. Since these organisms also had higher abundance after the inhibition phase, their cooperation could prevent anammox bacteria from nitrite inhibiting when the influent nitrite concentration was higher. The analysis of community and function shift is expected to emphasize the importance of functional bacteria in anammox process and provides a potential control strategy for nitrogen-containing wastewater treatment process.