Diversity and distribution of CO2-fixing microbial community along elevation gradients in meadow soils on the Tibetan Plateau

Abstract

Soil CO2-fixing microbes play a significant role in CO2-fixation in the terrestrial ecosystems, particularly in the Tibetan Plateau. To understand carbon sequestration by soil CO2-fixing microbes and the carbon cycling in alpine meadow soils, microbial diversity and their driving environmental factors were explored along an elevation gradient from 3900 to 5100 m, on both east and west slopes of Mila Mountain region on the Tibetan Plateau. The CO2-fixing microbial communities were characterized by high-throughput sequencing targeting the cbbL gene, encoding the large subunit for the CO2-fixing protein ribulose 1, 5-bisphosphate carboxylase/oxygenase. The overall OTU (Operational Taxonomic Unit) abundance is concentrated at an altitude between 4300 and 4900 m. The diversity of CO2-fixing microbes is the highest in the middle altitude area, and on the east slope is higher 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. Altitude has the greatest influence on the structural characteristics of CO2-fixing microbes, and other environmental factors are significantly correlated with altitude. Therefore, altitude influences the structural characteristics of CO2-fixing microbes by driving environmental factors. Our results are helpful to understand the variation in soil microbial community and its role in soil carbon cycling along elevation gradients.