Resilience Mechanisms of Farmland Bacteria to Elevated Cadmium and Drought in Limed Soils of Non-Ferrous Mining Regions

Bacteria are vital in paddy soils, but their responses to stresses like Cd wastewater irrigation or/and drought in farmland soils immobilized by years of lime application were unclear. Soils from nonferrous metals mining periphery agricultural areas, limed for three years, were collected for exogenous Cd invasion and drought incubation experiments and sampled over time. Results showed that bacterial diversity and community composition and function exhibited mild responses to exogenous Cd at day 31 and significant changes at day 58, with dominance of ecological niches of Cd-resistant genera Lysobacter, Sphingomonas, Pseudomonas and Streptomyces, and the resistance function began to be enriched. While drought triggered obvious changes in soil bacterial community composition and function, rather than diversity. The bacterial interaction network was sensitive to both Cd and drought, with the latter exhibiting a more pronounced disruptive effect, yet stability improved under dual stress. Our findings indicate that the genera demonstrating tolerance to both Cd and drought, and exhibiting positively associations with the active forms of Cd, predominantly belong to the Proteobacteria and Actinobacteria phyla. This research provides novel insights into the remediation of soil Cd.