Microbial Community Response to Photoelectrons and Regulation on Dolomite Precipitation in Marine Sediments of Yellow Sea

Dolomite exhibits a wide distribution in geological strata. The metabolic activities of microorganisms in marine sediments play a crucial role in the formation of dolomite. Semiconducting minerals, such as hematite, goethite, and rutile, generate photoelectrons when exposed to sunlight, which can impact the community structure and metabolic activities of microorganisms. In this study, a simulated photoelectron system was conducted to investigate the response of the microbial community, as well as the regulation of sulfate reduction, to photoelectrons using high-throughput sequencing of the 16S rRNA gene. The regulatory effect of semiconducting mineral photoelectrons on the induction of carbonate precipitation by sulfate-reducing bacteria was explored. X-ray diffraction and Raman spectroscopy were used to characterize carbonate precipitation. During cultivation, the pH values of the system increased from 8.0 to approximately 8.5 and the rate of sulfate reduction was significantly enhanced under the influence of simulated photoelectrons. The alpha diversity of the microbial community decreased, and the semiconducting mineral photoelectronic system had a promoting effect on the enrichment of sulfate-reducing bacteria, mainly Desulfovibrio. Under the regulation of photoelectrons, sulfate-reducing bacteria can effectively oxidize organic matter and reduce sulfate in the environment, and proto-dolomite can be formed at a low Mg/Ca ratio. This process has important implications for carbon and sulfur element cycling in estuarine and oceanic photic zones, and provides a new explanation for the formation of large amounts of dolomite in geological history.