High-throughput sequencing of 16S RNA genes of soil bacterial communities from a naturally occurring CO2 gas vent

Abstract

High-throughput sequencing was used to investigate the effects of CO2 emissions on the composition and structure of soil bacterial communities. Soil from an area (La Sima, Campo de Calatrava) where CO2 is released to the atmosphere from a naturally occurring gas vent venting structure. Soil samples were taken was sampled along a CO2 gradient. Bacterial community richness and diversity notably decreased with increasing CO2 flux. Bacterial community composition varied along the CO2 gradient: as CO2 flux increased, the relative abundance of Chloroflexi phylum increased, whereas the relative abundance of Acidobacteria, Verrucomicrobia and Gemmatiomonadetes phyla decreased. Within the Chloroflexi phylum, OTUs related to the genera Thermogemmatispora, Ktedonobacter and Thermomicrobium dominated bacterial communities sampled in sites with the highest CO2 flux. Canonical correspondence analysis (CCA) revealed that differences in bacterial communities were best explained by CO2 flux. The geological storage of CO2 has been proposed as a viable option for reducing anthropogenic CO2 contributions to atmospheric pools in order to mitigate the climatic change. These results are useful to evaluate the risk of potential CO2 leakages on ecosystems associated to geological storage of CO2.