Predominance of Bacillus sp in soil samples of the southern regions of Western Ghats, India

The aim of this study was to determine the bacterial diversity in soils of the southern region of the Western Ghats, a 'biodiversity hotspot', and thereby futher our understanding of the microbial communities in this ecological niche. The diversity and phylogeny of bacterial populations in soil samples collected from various locations of the Tamil Nadu and Kerala regions of Western Ghats were compared using both cultivation-dependent and cultivation-independent methods. A total of 171 bacterial strains were isolated based on their morphological characteristics and their diversity indices calculated. The distinctive amplified ribosomal DNA restriction analysis (ARDRA) pattern of each isolate was determined, and representative isolates were then subjected to 16S rRNA gene sequencing. On the basis of their sequence similarity, the isolates were distributed among three different genera belonging to Firmicutes (83.3 %), Proteobacteria (8.3 %) and high G+C Gram-positive bacteria (8.3 %). The highest and the lowest values for the diversity indices were obtained for metagenomic DNA extracted from isolates BWGA and BVP, respectively; these were used for 16S rRNA gene library construction and analysis. Based on their phylogenetic analysis, the predominant members of the habitat were found to belong to the phylum Firmicutes (84.62 %). Firmicutes was the dominant bacterial phylum detected by both approaches, but the culture-independent approach detected a considerably higher number of uncultivable bacteria. In conclusion, in our study of the bacterial diversity of this Western Ghats region, we fund that the genus Bacillus was predominant among the samples assessed by both cultivation-dependent and cultivation-independent methods.