Diversity And Distribution Of CO2-Fixing Microbial Community Along Elevation Gradients In Meadow Soils On The Tibetan Plateau

Soil CO 2 -fixing microbes play a significant role in CO 2 -fixation in the terrestrial ecosystems, particularly in the Tibetan Plateau. To understand carbon sequestration by soil CO 2 -fixing microbes and the carbon cycling in alpine meadow soils, microbial diversity and their driving environmental factors were explored along an elevation gradient from 3900m to 5100m, on both east and west slopes of Mila Mountain region on the Tibetan Plateau. The CO 2 -fixing microbial communities were characterized by high-throughput sequencing targeting the cbbL gene，encoding the large subunit for the CO 2 -fixing protein ribulose 1, 5-bisphosphate carboxylase/oxygenase. The overall OTU abundance is concentrated at an altitude between 4300m~4900m. The species richness and distribution uniformity on the east slope is better than those on the west slope. In terms of microbial community composition, Proteobacteria is dominant, and the most abundant genera are Cupriavidus , Rhodobacter , Sulfurifustis and Thiobacillus . The CO 2 -fixing microbial community structure dramatically shifted along the elevation. It was jointly driven by vegetation coverage, soil moisture content, and soil organic carbon and soil particle size, and most environmental factors are positively correlated. Our results are helpful to understand the variation in soil microbial community and its role in soil carbon cycling along elevation gradients.