669-8 Structure of Community of (Dizotrophs) Nitrogen-Fixing Bacteria.

See more from this Division: S03 Soil Biology & Biochemistry
See more from this Session: Soil Microbial Diversity and Function

Tuesday, 7 October 2008: 10:15 AM
George R. Brown Convention Center, 370C

Bo Sun1, Qihui Teng2, Zhongli Cui2 and Hui Cao2, (1)Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
(2)Key Laboratory of Microbiological Engineering of agricultural environment, MOA, Nanjing Agricultural University, Nanjing, China
Abstract:
Microorganisms involved in nitrogen fixation play important roles in the biosphere. Organic fertilizers are employed to improve red soil quality which are often N limited. To understand the effects of organic manure on the composition and structure of diazotrophs communities in red soils, the molecular diversity of diazotrophs was examined using a PCR based cloning approach with nifH as functional gene marker. The typical red soil was sampled from the Ecology Experiment Station of Red Soil in Jiangxi Province, China (281o20'N,and 116o53'E). The experiment included four treatments: the control (without fertilization), low organic manure (LM), high organic manure(HM) and high organic manure amended with lime(ML). The results of RFLP patterns demonstrated that the main pattern of clones accounted for overly (above) 82% in clone library of HM, about 50-60% in other libraries. nifH clones of the main pattern which were sequenced and identical with nitrogenase reductase (about 96% similarity) . Some of the clone sequences of LM library were related to nifH genes belonging to four phylogenetic subdivisions (Cyanobactera and ¦Á, ¦Â, ¦Ã subclasses of the Proteobacteria) in our phylogenetic tree, however the nifH genes of HM and ML library only belonging to the subdivision of Cyanobacteria. High P/N was the main reason which affected the diversity (communities) of diazotrophs in red soil. The nifH sequences of the dominant patterns in all libraries were most similar to sequences of the Cyanobacteria.

See more from this Division: S03 Soil Biology & Biochemistry
See more from this Session: Soil Microbial Diversity and Function