title: Molecular diversity of nitrogen-fixing bacteria from the Tibetan Plateau, China.
abstract: To understand the composition and structure of nitrogen-fixing bacterial communities from the Sanjiangyuan Nature Reserve on the Tibetan Plateau, the molecular diversity of nifH genes from soil obtained at six sites was examined using a PCR-based cloning approach. Six samples were collected from different regions at an altitude of 3907-4824 m above sea level, and a principal component analysis (PCA) showed that they had different biogeochemical properties. A total of 446 clones and 162 unique RFLP patterns were found. PCA of the RFLP patterns and their biogeochemical parameters showed that the content of soil organic carbon (C), total nitrogen (N) and altitude were the most important factors affecting the nitrogen-fixing bacteria community. Fifty-nine nifH clones were sequenced and their nucleotide identity varied from 64% to 98%, subdivisible into four groups in our phylogenetic tree. Some of the clone sequences were related to nifH genes belonging to four phylogenetic subdivisions (alpha, beta, gamma and delta subclasses of the Proteobacteria), while most of the clones were closely related to the genes of the uncultured bacteria. The tree also showed that the sequence distributions were not clearly related to the sample sites.
authors.affiliation: Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, and The Key Laboratory of Forest Ecology and Environment of State Forestry Administration, Beijing 100091, China.
authors.forename: Yuguang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Diqiang
authors.initials: D
authors.lastname: Li
authors.forename: Huimin
authors.initials: H
authors.lastname: Wang
authors.forename: Qiming
authors.initials: Q
authors.lastname: Xiao
authors.forename: Xueduan
authors.initials: X
authors.lastname: Liu
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics; D002681:China; D003001:Cloning, Molecular; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D010088:Oxidoreductases / Q000235:genetics*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D020560:Proteobacteria / Q000145:classification / Q000235:genetics; D017422:Sequence Analysis, DNA; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology
chemical_list: D012987:Soil; D010088:Oxidoreductases; C029130:nitrogenase reductase