Mechanistic Effects of High-Fluoride Hot Springs on Microbial Community Structure and Diversity

To elucidate the influence of high-fluoride hot springs on microbial community structure and diversity, 5 hot spring samples and 12 other water samples were collected along the Checun-Lushan, Luanchuan-Lushan, and Luonan-Gushi fault zones on July 8, 2024. Water chemistry analysis and 16S rRNA gene sequencing of the V3/V3+V4/V6 regions were performed. The results show that the five hot springs exhibited an average F-content of 15.04 mg/L, with weakly alkaline pH, high total dissolved solids, and Na+ as the dominant cation. The hydrochemical type was classified as HCO3 SO4-Na, consistent with the chemical characteristics of high-fluorine water. Microbial abundance and diversity were significantly reduced in the hot springs as compared to the surface water and groundwater samples. The dominant phyla in the study area included Proteobacteria, Cyanobacteria, Bacteroidetes, and Actinobacteria. The genus-level composition varied significantly across samples, with no dominant genus observed universally. Redundancy analysis of the top 11 phylum-level species by abundance in water samples revealed that eight species were negatively correlated with the F- content, while only three were positively correlated. High-fluoride hot springs influence the formation of microbial communities in groundwater, with the presence of F- exerting inhibitory effects on microbial growth.