Deciphering the diversity of aerobic culturable thermophiles in hot springs of Manikaran, Himachal Pradesh

For deciphering aerobic culturable diversity of thermophiles from Manikaran hot springs three different types of samples viz water, soil sediment and biomat were collected from upper Manikaran, lower Manikaran and Shangna. The temperature of water was found to be significantly higher at upper Manikaran and lowest at Shangna. But no significant difference was observed in pH of water and soil sediment samples. A total of 108 bacterial isolates were obtained. The percentage of the isolates obtained from on site culturing and standard plate count technique was recorded as 15 and 75 respectively. Only 16 per cent of the total isolates could be obtained through trait specific enrichment technique. Nutrient agar and broth were found to be the most appropriate media for the isolation of thermophiles. Screening of all the isolates for temperature tolerance revealed that majority of them were facultative (58.33%) followed by thermotolerant (21.30%) and obligate thermophiles (20.37%). A significantly higher bacterial load was observed in biomat (5.44 log CFU/ml) as compared to soil sediment (4.84 log CFU/ml) and water (4.13 log CFU/ml) samples. No definite trend was observed in the distribution of actinomycetes population in water, soil sediment and biomat samples. No fungal isolate was obtained from all types of samples. Among all the isolates 77.78 per cent of the isolates were Gram positive, rod shaped, spore forming bacteria while 22.22 per cent were Gram negative, rod shaped, non-spore formers thereby indicating the dominance of these bacteria in Manikaran hot springs.