Soil-dependent responses of bacterial communities, phosphorus and carbon turnover to uranium stress in different soil ecosystems

Uranium (U) can impact microbially driven soil phosphorus (P) and carbon (C) cycling. However, the response of microbial P and C turnover to U in different soils is not well understood. Through the quantitative assay of P pools and soil organic C (SOC) quantitative assay and sequencing of 16S rRNA gene amplicons and metagenomes, we investigated the effect of U on P and C biotransformation in grassland (GL), paddy soil (PY), forest soil (FT). U (60 mg kg⁻¹) impacted the diversity, interaction and stability of soil bacterial communities, leading to a decrease in available P (AP). Under U stress, organophosphate mineralization substantially contributed to the AP in GL and FT, whereas intracellular P metabolism dominated the AP in PY. Also, the reductive citrate cycle (rTCA cycle) promoted the content of SOC in GL, while the rTCA cycle and complex organic C degradation pathways enhanced the SOC in PY and FT, respectively. Notably, functional bacteria carrying organic C degradation genes could decompose SOC to enhance soil AP. Bacteria developed various resistance strategies to cope with U stress. This study reveals soil-dependent response of microbial P and C cycling and its ecological functions under the influence of radioactive contaminants in different soil systems.