Salt Marsh Raw sequence reads. soil metagenome

Human activity has doubled reactive nitrogen to the biosphere. Understanding the response of microorganisms to global nitrogen enrichment is critical to predicting ecosystem change. We investigated effects of long-term nitrogen enrichment on the microbial community in salt marshes, one of the most nitrogen-enriched ecosystems in the world, via high-throughput sequencing of the 16S rRNA gene and its gene product (16S rRNA). We show that a decade of nitrogen-enrichment caused the proportion of dormant microbes to double, from 45% to 90%, among the highest proportions reported. This increase in dormancy was accompanied by a continual decrease in diversity of active microbes. Our results indicate that despite reductions in active diversity the microbial community maintains a genetic reservoir of traits necessary to respond to future environmental perturbation.