Sustained bacterial N2O reduction at acidic pH

Abstract

Nitrous oxide (N₂O) is a climate-active gas with emissions predicted to increase due to agricultural intensification. Microbial reduction of N₂O to dinitrogen (N₂) is the major consumption process but microbial N₂O reduction under acidic conditions is considered negligible, albeit strongly acidic soils harbor nosZ genes encoding N₂O reductase. Here, we study a co-culture derived from acidic tropical forest soil that reduces N₂O at pH 4.5. The co-culture exhibits bimodal growth with a Serratia sp. fermenting pyruvate followed by hydrogenotrophic N₂O reduction by a Desulfosporosinus sp. Integrated omics and physiological characterization revealed interspecies nutritional interactions, with the pyruvate fermenting Serratia sp. supplying amino acids as essential growth factors to the N₂O-reducing Desulfosporosinus sp. Thus, we demonstrate growth-linked N₂O reduction between pH 4.5 and 6, highlighting microbial N₂O reduction potential in acidic soils.

Microbial reduction of nitrous oxide to dinitrogen is considered negligible under acidic conditions. However, Guang He et al. show that a co-culture of two bacterial species derived from acidic tropical forest soil can reduce nitrous oxide at pH 4.5.