Core autotrophic microbes drive functional stability of soil cbbL-containing autotrophic microbes during desertification

Abstract

The desertification process is characterized by the degradation of soil habitats and attenuation of plant biomass, leading to decreased soil carbon (C) input and increased environmental stress gradients of soil microbes. C dioxide assimilation driven through autotrophic microorganisms is the main process of soil C cycling, and the ecological role of autotrophic microbes is critical for soil C sequestration. However, the feedback dynamics of autotrophic microbes and their functional activity in soil profiles during desertification have not been explored. Here, we analysed three typical stages of desertification (potential, moderate and severe desertification) by high-throughput sequencing and enzyme activity assays to investigate the variation trends of autotrophic microbes and the maintenance of C fixation activity along soil profiles (0–100 cm) as desertification proceeded. We found that the desertification process reduced the abundance and diversity of autotrophic microbes, but increased the activity of soil microbial C fixation enzymes, which highlights the importance of microbial CO2 fixation in oligotrophic soil profiles in desert ecosystems. In particular, we demonstrated that core autotrophic microbes drove the compositional difference of autotrophic microbes, which in turn affected soil C fixation activity, suggesting that core autotrophic microbes are critical for maintaining C sequestration during desertification. Taken together, these results strengthen our comprehension of the factors driving soil functional stability and emphasize that core microbes should be viewed as pivotal factors in maintaining functional activity and ecosystem sustainability during desertification.