Elevated CO(2) influences microbial carbon and nitrogen cycling

BACKGROUND: Elevated atmospheric CO(2) (eCO(2)) has been shown to have significant effects on terrestrial ecosystems. However, little is known about its influence on the structure, composition, and functional potential of soil microbial communities, especially carbon (C) and nitrogen (N) cycling. A high-throughput functional gene array (GeoChip 3.0) was used to examine the composition, structure, and metabolic potential of soil microbial communities from a grassland field experiment after ten-year field exposure to ambient and elevated CO(2) concentrations. RESULTS: Distinct microbial communities were established under eCO(2). The abundance of three key C fixation genes encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), carbon monoxide dehydrogenase (CODH) and propionyl-CoA/acetyl-CoA carboxylase (PCC/ACC), significantly increased under eCO(2), and so did some C degrading genes involved in starch, cellulose, and hemicellulose. Also, nifH and nirS involved in N cycling were significantly stimulated. In addition, based on variation partitioning analysis (VPA), the soil microbial community structure was largely shaped by direct and indirect eCO(2)-driven factors. CONCLUSIONS: These findings suggest that the soil microbial community structure and their ecosystem functioning for C and N cycling were altered dramatically at eCO(2). This study provides new insights into our understanding of the feedback response of soil microbial communities to elevated CO(2) and global change.