Effects of different vegetation on autotrophic carbon fixation capacity and autotrophic microbial community in karst soil

The process of autotrophic carbon fixation can make considerable contribution to soil organic matter (SOM). However, the effects of different vegetation on the capacity of autotrophic carbon fixation and the autotrophic microbial community were not clear. In this study, we used 13C (13CO2) isotope labelling combing cross-polarization with magic angle spinning (CP-MAS) 13C nuclear magnetic resonance (NMR) and metagenomics to investigate the autotrophic carbon fixation capacity and autotrophs community of four typical soils (Alfalfa field, shrubland, cornfield and bare land) in a control karst experiment site. The 13C-NMR analysis showed that the 13CO2 was incorporated into the different chemical categories in SOM. The vital autotrophs mostly belong to Actinobacteria, and ammonia oxidizer play an important role. These results showed that the photoautotrophy was the primary in topsoil, while the chemolithoautotrophy plays an important role in carbon cycle of karst soil. Meanwhile we provided direct evidence of autotrophic inorganic carbon fixation with 13C-NMR and statistical evidence of autotrophic microbe community in karst different land-use soils.