Soil nitrous oxide reducing microbial communties

N2O is a potent greenhouse and ozone layer depleting gas. Agricultural soils are the main source of N2O and N-fertilization further enhances N2O emssions. The only known biological sink of N2O in soil is microbial reduction of N2O to N2 catalysed by the N2O reductase enzyme encoded by nosZ gene found in denitrifying and non-denitrfiying microorganisms. The overall diversity of N2O reducers is divided into two groups termed nosZ clades I and II, based on the phylogeny of the nosZ gene. Carbon (C) availability is a key factor in determining microbial community composition in soil. It also regulates denitrification rates as well as affects the composition of denitrifying microbial communities in soil. However, how C substrate complexity and availability control the community composition, diversity and abundance of N2O reducing microorganisms in soil is poorly understood.The objective was to examine the effect of differences in C substrate complexity on N2O consuming microbial communities in soils. Specifically, we investigate niche partitioning of genetically distinct N2O reducers in soil and, by linking specific N2O reducing phylotypes to particular C-substrates, determine if carbon preferences are associated with specific lineages in the nosZ phylogeny