Culture dependent diversity and phylogeny of thermophilic bacilli from a natural hot spring reservoir in the Gir Forest, Gujarat (India)

The thermophilic bacteria, isolated from a natural hot spring reservoir, Tulsi Shyam (Gir Forest, Gujarat, India) were characterized and diversified using the conventional approaches; Gram reaction, cell morphology, growth patterns, biochemical properties and antibiotic sensitivity. The bacteria were Gram positive, rod shaped and catalase positive. Majority of them produced amylase, indicating their ecological and biotechnological significance. The bacteria were further categorized on the basis of the amplified ribosomal DNA restriction analysis (ARDRA) patterns, generated by a tetracutter RE, HaeIII. As a polyphasic taxonomy approach, the isolates were clustered into 9 different groups, based on the conventional approaches and the ARDRA patterns. The further analysis was based on the 16S rRNA gene sequencing. The trend suggested that the phenotypic and phylogenetic diversity data considerably coincided. Overall, the part of Tulsi Shyam hot spring bacterial community represented by cultivated aerobic organotrophs can be clustered into 3 Genera, Anoxybacillus, Geobacillus/Aeribacillus and Bacillus. They can further be grouped into sub-clusters at the species level to establish phylogenetic and phenotypic relationship. Further, the diversity indices; Simpson’s index, Dominance index and Shannon index indicated the species diversity, species richness and distribution evenness, respectively. A lower Simpson’s index (0.1905) and higher Dominance index (0.8095) revealed significant bacterial diversity. While a higher Shannon index (2.987) suggested evenness in the bacterial distribution in different soil and water samples. The lower values of Berger-Parker Dominance index and Ginni coefficient supported the trends of the Shannon index. As the studied habitat was not earlier explored for the bacterial diversity, the findings would significantly add to the knowledge of the cultivation based microbial diversity.