Rates and microbial communities of denitrification and anammox across coastal tidal flat lands and inland paddy soils in East China

Denitrification and anammox are the main pathways of N loss in wet habitats while their relative contribution to N-2 production and underlying microbial mechanisms across marine-terrestrial ecotone remain unclear. Here we investigated the rates of anammox and denitrification, and the distribution patterns of anammox bacteria and nosZ Glade I and II denitrifiers across coastal tidal flat to inland paddy soils. Results showed that denitrification dominated the N-2 production over anammox in all samples, accounting for 87.1%-100% of total N-2 production. Coincident with the rate, the abundance of nosZ Glade I and II genes were 1-2 orders of magnitude higher than those of hzsB gene. The community of anammox bacteria was mainly driven by salinity while nosZ Glade I and II denitrifiers communities were mainly determined by both salinity and pH. Alphaproteobacteria dominated in the nosZ Glade I community in all samples while Betaproteobacteria and Gammaproteobacteria were mainly present in low salinity wetland and paddy soils. The nosZ Glade II community was composed of more phyla, in which Bacteoidetes and Chloroflexi were ubiquitous while Gemmatimonadetes was present only in low salinity wetland and paddy soils. These findings have direct implications for explicitly incorporating both nosZ Glade I and II into future N loss estimation and N2O mitigation in marine-terrestrial ecotone.

Automated summary

Denitrification and anammox are the main pathways of nitrogen loss in wet habitats, with denitrification dominating the N-2 production. The community of denitrifiers, driven by nosZ Glade I and II genes, is mainly influenced by salinity and pH, while the anammox bacteria community is mainly affected by salinity.