Coal-mining subsidence changed distribution of the microbiomes and their functional genes in a farmland

Abstract

Land subsidence is a serious geological event, and can trigger severe environmental and ecological issues. In this study, the influences of coal-mining subsidence on distribution of farmland microbiomes and their functional genes were investigated by 16 S ribosomal RNA (rRNA) gene and metagenome sequencing. The results showed the existence of a core microbiome, which determined the community compositions across the subsidence farmland. Subsidence decreased the relative abundances of dominant Streptomyces, Nocardioides, and Rhizophagus, but increased the relative abundances of dominant Bradyrhizobium, Rhizobium, and Trichoderma. Subsidence also decreased the relative abundances of genes related to carbon metabolism, Quorum sensing, aminoacyl-transfer RNA (tRNA) biosynthesis, and oxidative phosphorylation, and increased the relative abundances of genes related to two-component system and bacterial chemotaxis. Furthermore, subsidence weakened the biosynthesis of organic carbons by decreasing the relative abundances of genes encoding glycosyl transferases, and strengthened decomposition of degradable organic carbons of the microbiomes and auxiliary activities by increasing the relative abundances of genes encoding glycoside hydrolases and polysaccharide lyases. The concentrations of total phosphorus, Mg²⁺ , and Ca²⁺ at the lower areas were significantly higher than those at the upper areas, indicating an associated loss of soil nutrients. Canonical correspondence analysis showed that soil moisture, pH, and the concentrations of NH₄ ⁺ and Ca²⁺ were the main factors affecting the distribution of the microbiomes and their functional genes. Collectively, this study shows that coal-mining subsidence alters soil physicochemical properties and distribution of farmland microbiomes and their functional genes.

Keywords: coal-mining subsidence; farmland; functional gene; metagenomics; microbiome.