Increased heterogeneity of sedimentary potential silicate-solubilizing bacterial communities caused by cascade...

Despite the crucial role of silicate mineral biological weathering in silicon cycling and morphogenesis, our understanding of the microbial communities involved in this process remains limited, especially in rivers affected by cascade damming. Here, we combined field sampling and literature search to establish a comprehensive information table of potential silicate-solubilizing bacteria (PSSB) in sediments of the Jinsha River, a large cascade dam-impacted river in China. We investigated the community structures, biogeographic patterns, and co-occurrence patterns of PSSB in sediments and explored their responses to cascade dam construction. Our analyses revealed significant differences in PSSB community structure between the upstream natural reach and cascade dam reach. The alpha diversity of the PSSB communities was significantly lower, while beta diversity was higher in the cascade dam reach compared to the upstream natural reach. Beta diversity was predominantly shaped by turnover along the river, which was higher in the cascade dam reach. Community assembly analyses indicated that both environmental filtering and dispersal limitation shaped PSSB biogeographic patterns, yet stochastic processes predominated, particularly within the upstream natural reach. Co-occurrence network analyses demonstrated that PSSB tended to favor cooperative interspecific patterns. Cascade dam construction reduced the complexity of PSSB communities but promoted stability. Phylum Bacteroidetes comprised a substantial proportion (59 %) of keystone OTUs, highlighting their crucial role in networks. This study highlights cascade dam construction's effects on sedimentary PSSB communities in riverine ecosystems, offering novel insights into the biological weathering of silicate minerals and river sedimentary silicon cycling.