Response of microbial communities to supercritical CO2 and biogeochemical influences on microbially mediated CO2-saline-sandstone interactions

In this study, laboratory experiments were conducted to investigate the influences of supercritical CO2 (scCO2) on the indigenous microbial communities. Results revealed that the abundance of gene copies (mL− 1) in samples and the shifts in the microbial community were strongly affected by scCO2 injection. Furthermore, Proteobacteria showed better ability of tolerance to the scCO2 injection than Firmicutes in initial period and both of them were the predominant phyla after 180 days' experiments. In addition, the acidogenic mineral-attached biofilms formed by Pseudomonas stutzeri, Acinetobacter soli etc. surrounding the feldspars and clays could lower the pH in solution and accelerate the dissolution of silicate minerals. As the secondary carbon sink minerals, amount of CaCO3 and FeCO2 were observed in the microbially mediated CO2-saline-sandstone interactions, demonstrated the Fe(III)-reducing microbes (Shewanella putrefaciens, Citrobacter sp. LAR-1 and Pseudomonas fluorescens) could reduce the Fe(III) released from clays to Fe(II) and induce siderite biomineralization through metabolic processes.