Analysis of diversity of actinomycetes from arid and saline soils at Rajasthan, India

Actinomycetes are ubiquitous microbes with a variety of applications in industry and medicine. It is well known that different ecosystems harbour unique microbial populations, that is, bacterial diversity can be influenced by geography and ecology. Diversity studies of actinomycetes from extreme habitats in Rajasthan state of India was carried out in this study. The Sambhar salt lake and arid regions (sand dunes in Thar Desert and stone quarries) were mainly studied to understand the prevalence of halotolerant and xerotolerant actinomycetes. Isolation was done on selective media followed by morphological studies, estimation of diversity and 16S rDNA gene sequencing. All the samples had both streptomycete and non-streptomycete populations and the dominance values for sand dunes and salt lake ranged from 0.14 to 0.36 which indicate even spread or equal dominance of taxa. For taxon specific communities, the dominance values range from 0.13 to 0.43 confirming the existence of Streptomyces diversity. Actinomycetes represented nearly 77% of the culturable bacterial population in Sambhar salt Lake which could be due to their ability to survive in conditions of stress and adapt to the extremes in the environment. 16S rRNA gene sequences of few isolates from Rajasthan exhibited resemblance to isolates from geographically distant Sahara Desert (Tunisian section). 16S rRNA gene sequences suggest the isolates obtained from the Thar Desert and salt lake could be novel strains.