Peatland microbiomes after protist feeding

Temperature significantly impacts microbial communities' composition and function, which subsequently plays a vital role in the global carbon cycle, potentially exacerbating climate change. Recent research indicates that the interactions between different microorganisms might be critical in shaping how these communities react to temperature changes. Nonetheless, we still lack a comprehensive understanding of how predation influences microbial communities in future climate scenarios. Here, we assess whether predation by key bacterial consumer - ciliates - influences a microbial community's freshwater temperature and nutrient response regarding biomass, diversity, structure, and function. In a three-week microcosm experiment, we exposed mostly prokaryotic microbial communities to a community of ciliate predators at two different field-relevant, climate relevant temperatures and nutrient levels, reflective of forecasted climate shifts. Nutrients, temperature, and ciliate presence influenced microbial biomass and function. Interestingly, however, the interaction between nutrients, temperature, and ciliate presence more comprehensively explained the observed changes in microbial community biomass, structure, and function. Our study supports previous findings that temperature and nutrients are essential drivers of microbial community structure and function but also demonstrates that the presence of predators can mediate microbial community, prey, microbiome and their responses to warming.