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.

Bacterial diversity analysis of Yumthang hot spring, North Sikkim, India by Illumina sequencing

“…There are studies supporting and substantiating findings of the present study that bacterial communities in the hot springs located on the high altitude are dominated by Proteobacteria [12]. Similar observations have been made by [13,14] that geographic locations play a significant role in bacterial community structure. Proteobacteria has also been reported from many studies based on the 16SrRNA analysis of hot springs with moderately high and very high temperatures (44-110°C) at various geographical locations, including India [15][16][17].…”

Bio-prospecting Bacterial Diversity of Hot Springs in Northern Himalayan Region of India for Laccases

“…This variation may be due to high temperature and altitude of the studied hot spring where oxygen concentration is low. Another study [8] reported aerobic culturables only from Ladakh hot springs, and found Proteobacteria, Firmicutes and Actinobacteria but not Bacteroidetes. Paludibacter does not require oxygen, nitrate, sulfate, thiosulfate, elemental sulfur, sulfite, and Fe(III) nitrilotriacetate as terminal electron acceptors [18].…”

“…1 g soil sample with 9 ml of hot spring water was shaken for 1 h with glass beads on a horizontal shaker. This soil suspension was centrifuged and supernatant was used for assaying the activity using 2 mM ABTS at different pH (5,6,7,8) and temperatures (55-75°C).…”

“…However, thermostable laccase producers identified till now are very few in comparison to total microbes present in hot springs. Despite previous effort [8], a comprehensive census of the bacterial community in hot springs of Nubra valley is still lacking as only culturable diversity was studied.…”