Bacterial diversity and community structure of Western Indian Himalayan red kidney bean (Phaseolus vulgaris) rhizosphere as revealed by 16S rRNA gene sequences

Agriculture is an important livelihood activity in the Himalayan regions. Our previous studies revealed the presence of diverse diazotrophic assemblage in indigenous red kidney bean (RKB) rhizospheric soil from two different locations of Western Indian Himalaya, namely S1 (Chhiplakot, 30.70° N/80.30° E) and S2 (Munsyari, 30.60° N/80.20° E), selected on the basis of real-time PCR analysis. In this study, two 16S rRNA gene clone libraries (SB1 and SB2, respectively) were constructed using the same rhizospheric soil samples for assessing the total bacterial diversity and their community structure. A total of 760 clones were obtained, with ≈54–59% of these sequences belonging to the phylum Proteobacteria. While sequences belonging to Bacteroidetes, Chloroflexi, Acidobactria, Planctomycetes, Firmicutes, Nitrospira, Gemmatimonadetes, Cyanobacteria, Verrucomicrobia, OD1, OP11 and Actinobacteria were encountered in both the soils, sequences belonging to bacteria from the classes Chlorobi and BRC1 were only detected in the S1 soil. Both the libraries showed similar bacterial community compositions, with Pseudomonas (≈33–34%) as predominant genus. Phylogenetic analysis revealed that all the clone sequences were clustered in different bacterial groups as per their resemblance with their respective phylogenetic neighbours. Major clusters were formed by Gammapreoteobacteria followed by Bacteroidetes and Alphapro-teobacteria. A good fraction of the clone sequences has no resemblance with existing groups, thereby suggesting the need of culture-dependent studies from Himalayan regions. To the best of our knowledge, this study is the first major metagenomic effort on Himalayan RKBs rhizobacteria revealing fundamental information that needs to be explored for functional studies.