Evaluating the Diversity of Culturable Thermotolerant Bacteria from Four Hot Springs of India

Abstract

The culturable bacterial diversity of four hot springs of India was analysed, employing different media and screened for temperature tolerance (40°C - 70°C). Sixty morphotypes from Bakreshwar, 48 from Balrampur, 46 from Chumathang and 52 from Vashist were obtained. A set of 112 isolates, tolerant to 45°C and above, were analysed employing Amplified ribosomal DNA restriction analysis (ARDRA). Sequencing of 16S rRNA gene of the representative isolates revealed that 86%, 93%, 44% and 44% of the isolates respectively from Bakreshwar, Balrampur, Chumathang and Vashist, belonged to Firmicutes. Members of Actinobacteria were present in all the four hot springs, while Proteobacteria were present only in Chumathang and Vashist and Bacteroidetes found only in Bakreshwar. This is the first report of Aurantimonas and Brevundimonas in hot springs. Biolog analyses of three isolates, growing at or above 60°C revealed unique abilities, in terms of utilization of substrates and resistance patterns.