Mitomycin C-induced prophage activation for exploring the Lysogeny-lysis functional dynamics in situ

Temperate phages, which alternate between lysogenic and lytic cycles, are key regulators of microbial communities and ecosystem functions. Yet, the ecological consequences of prophage activation in soil remain poorly understood. Here, we developed a novel in situ mitomycin C (MMC) induction assay to investigate the functional impacts of prophage activation on microbial communities and soil biogeochemistry. Using a gradient of MMC concentrations, we identified 0.1 μg/mL as an optimal dose that efficiently induced prophages with minimal cytotoxicity to non-lysogenic bacteria. Microcosm experiments in black and laterite soils revealed that prophage induction significantly altered bacterial community composition and diversity, and disrupted carbon and nitrogen cycling. Specifically, low-dose MMC treatments suppressed nitrogen mineralization, while higher doses impaired microbial respiration and reduced CO₂ and N₂O emissions. These findings demonstrate that prophage activation serves as a sensitive indicator of soil microbial dynamics and nutrient turnover, offering new insights into the roles of temperate phages in terrestrial ecosystem functioning.