Network analysis of 16S rRNA sequences suggests microbial keystone taxa contribute to marine N2O cycling

• Published in: Communications biology 2023-02, Vol.6 (1), p.212-14, Article 212
• Main Authors: Jameson, Brett D., Murdock, Sheryl A., Ji, Qixing, Stevens, Catherine J., Grundle, Damian S., Kim Juniper, S.
• Format: Article
• Language: English
• Subjects: 631/326/171/1878; 631/326/2565/855; 631/45/47/4112; Basins; Biogeochemistry; Biology; Biomedical and Life Sciences; Carbon; Carbon cycle; Community structure; Ecosystem biology; Ecosystems; Genes; Heterotrophs; Life Sciences; Metabolism; Nitrification; Nitrogen; Nitrous oxide; Organic matter; Organisms; Remineralization; rRNA 16S; Taxonomy; Water column
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-023-04597-5

The mechanisms by which large-scale microbial community function emerges from complex ecological interactions between individual taxa and functional groups remain obscure. We leveraged network analyses of 16S rRNA amplicon sequences obtained over a seven-month timeseries in seasonally anoxic Saanich Inlet (Vancouver Island, Canada) to investigate relationships between microbial community structure and water column N 2 O cycling. Taxa separately broadly into three discrete subnetworks with contrasting environmental distributions. Oxycline subnetworks were structured around keystone aerobic heterotrophs that correlated with nitrification rates and N 2 O supersaturations, linking N 2 O production and accumulation to taxa involved in organic matter remineralization. Keystone taxa implicated in anaerobic carbon, nitrogen, and sulfur cycling in anoxic environments clustered together in a low-oxygen subnetwork that correlated positively with nitrification N 2 O yields and N 2 O production from denitrification. Close coupling between N 2 O producers and consumers in the anoxic basin is indicated by strong correlations between the low-oxygen subnetwork, PICRUSt2-predicted nitrous oxide reductase ( nosZ ) gene abundances, and N 2 O undersaturation. This study implicates keystone taxa affiliated with common ODZ groups as a potential control on water column N 2 O cycling and provides a theoretical basis for further investigations into marine microbial interaction networks. Network analysis of 16S rRNA-sequencing data collected over six months in the Sannich Inlet on Vancouver Island, Canada, suggests keystone microbial taxa that might contribute to water column N2O production and accumulation.