ABSTRACT
Although the Amazon Basin is well known for its diversity of flora and fauna, this report represents the first description of the microbial diversity in Amazonian soils involving a culture-independent approach. Among the 100 sequences of genes coding for small-subunit rRNA obtained by PCR amplification with universal small-subunit rRNA primers, 98 were bacterial and 2 were archaeal. No duplicate sequences were found, and none of the sequences had been previously described. Eighteen percent of the bacterial sequences could not be classified in any known bacterial kingdom. Two sequences may represent a unique branch between the vast majority of bacteria and the deeply branching, predominantly thermophilic bacteria. Five sequences formed a clade that may represent a novel group within the class Proteobacteria. In addition, rRNA intergenic spacer analysis was used to show significant microbial population differences between a mature forest soil and an adjacent pasture soil.
Subject(s)
Bacteria/genetics , RNA, Ribosomal/genetics , Soil Microbiology , Bacteria/classification , Bacteria/isolation & purification , Base Sequence , Brazil , DNA, Bacterial/analysis , Forestry , Gene Library , Genetic Variation , Molecular Sequence Data , Molecular Structure , Phylogeny , Polymerase Chain Reaction/methods , RNA, Ribosomal/chemistry , Sequence Analysis, DNAABSTRACT
The Brazilian inoculant strains 29W and 587 were found to be members of Bradyrhizobium elkanii primarily on the basis of 16S rRNA gene sequences identical to that of B. elkanii USDA76 and on the basis of reactivity with antibodies against serogroups 76 and 31, respectively. The agronomic consequences of using strains of B. elkanii as soybean inoculants are discussed.