Temperature Promotes Soil Microbial Competitive Dominance by Modulating Metabolic Interactions

Modern coexistence theory quantifies niche and fitness differences to elucidate species competition mechanisms, yet its application to temperature-driven shifts in soil microbial competitive outcomes remains limited. Here, we observed that high temperatures intensified competition among abundant bacterial genera in soil incubation experiments, particularly leading to the competitive dominance of Pseudomonas over Rhodococcus. Specifically, in competitive experiments involving Rhodococcus erythropolis NSX2 and Pseudomonas aeruginosa SB, SB successfully outcompeted NSX2, achieving a dominance of 61.6 % at 32 degrees C. This competitive dominance correlated with increased niche differences (from 0.45 to 0.88) and reduced fitness differences (from 0.83 to 0.35) at higher temperatures. Additionally, single-cell Raman spectroscopy and metabolite analysis revealed that high temperature enhanced cross-feeding, resulting in the production of more beneficial metabolites and fewer antibacterial quinolones. When metabolites served as the sole carbon source under high-temperature conditions, the growth and population density of SB were significantly promoted. These findings underscore the pivotal role of temperature in shaping soil microbial competitive dominance by regulating metabolic interactions. This study advances our understanding of soil microbial competition within the framework of modern coexistence theory. By integrating the theory with metabolic analysis, this work highlights the importance of temperature-dependent microbial interactions in changing ecosystems.