title: Diversity and distribution of autotrophic microbial community along environmental gradients in grassland soils on the Tibetan Plateau.
abstract: Soil microbial autotrophs play a significant role in CO2 fixation in terrestrial ecosystem, particularly in vegetation-constrained ecosystems with environmental stresses, such as the Tibetan Plateau characterized by low temperature and high UV. However, soil microbial autotrophic communities and their driving factors remain less appreciated. We investigated the structure and shift of microbial autotrophic communities and their driving factors along an elevation gradient (4400-5100 m above sea level) in alpine grassland soils on the Tibetan Plateau. The autotrophic microbial communities were characterized by quantitative PCR, terminal restriction fragment length polymorphism (T-RFLP), and cloning/sequencing of cbbL genes, encoding the large subunit for the CO2 fixation protein ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). High cbbL gene abundance and high RubisCO enzyme activity were observed and both significantly increased with increasing elevations. Path analysis identified that soil RubisCO enzyme causally originated from microbial autotrophs, and its activity was indirectly driven by soil water content, temperature, and NH4 (+) content. Soil autotrophic microbial community structure dramatically shifted along the elevation and was jointly driven by soil temperature, water content, nutrients, and plant types. The autotrophic microbial communities were dominated by bacterial autotrophs, which were affiliated with Rhizobiales, Burkholderiales, and Actinomycetales. These autotrophs have been well documented to degrade organic matters; thus, metabolic versatility could be a key strategy for microbial autotrophs to survive in the harsh environments. Our results demonstrated high abundance of microbial autotrophs and high CO2 fixation potential in alpine grassland soils and provided a novel model to identify dominant drivers of soil microbial communities and their ecological functions.
authors.affiliation: Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China. gxguo@itpcas.ac.cn.
authors.forename: Guangxia
authors.initials: G
authors.lastname: Guo
authors.affiliation: Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China. wdkong@itpcas.ac.cn.
authors.forename: Weidong
authors.initials: W
authors.lastname: Kong
authors.affiliation: Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Jinbo
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of Tibetan Environmental Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Jingxue
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Haodong
authors.initials: H
authors.lastname: Du
authors.affiliation: Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Xianzhou
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China.|Guizhou Key Laboratory for Mountainous Environmental Information and Ecological Protection, Guizhou Normal University, Guiyang, 550001, China.
authors.forename: Pinhua
authors.initials: P
authors.lastname: Xia
mesh_terms: D064751:Ammonium Compounds / Q000032:analysis; D001105:Archaea / Q000145:classification* / Q000201:enzymology / Q000235:genetics; D052818:Autotrophic Processes; D001419:Bacteria / Q000145:classification* / Q000201:enzymology / Q000235:genetics; D058448:Biota; D016000:Cluster Analysis; D065948:Grassland; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013696:Temperature; D018609:Tibet; D014867:Water / Q000032:analysis
chemical_list: D064751:Ammonium Compounds; D012987:Soil; D014867:Water; D012273:Ribulose-Bisphosphate Carboxylase
keywords: CO2 fixation; Elevation; Grassland; RubisCO; Tibetan Plateau