Temperature sensitivity of bacterial species-level preferences of soil carbon pools

Abstract

Soil organic carbon (SOC) mineralization, driven by soil microbial communities, plays a crucial role in the global carbon cycle. However, the temperature sensitivity of microbial preferences for SOC substrates remains poorly understood, limiting our ability to predict SOC dynamics under climate change. Here we combined bacterial community profiling, laboratory incubations, and a pool-based carbon model to investigate the relationships between bacterial species abundances and two SOC pools with fast and slow decay rates, respectively, at different incubation temperatures. Only about half of identified bacterial species is significantly (P < 0.05) associated with the mineralization of the two pools and their temperature sensitivity (Q₁₀). More importantly, we find that the association of the species with the two pools shifts in terms of both magnitude and direction with incubation temperature. The proportion of species associated with the Q₁₀ of fast pool decreased, while those associated with the Q₁₀ of slow pool increased with warming. Meanwhile, species specifically associated with the fast pool exhibit stronger temperature sensitivity compared to species specifically associated with the slow pool at lower temperatures, and vice versa at higher temperatures. These results suggest that common bacterial species associated with SOC mineralization adjust their substrate preferences in response to temperature variations, potentially impacting SOC composition and dynamics under warming.