Résumé
A total of 41 isolates were obtained from various samples (soil, mud, and water) of Surajkund hot spring, Jharkhand, atthree different isolation temperatures of 50C, 60C, and 70C. However, our interest was in the thermophilic strains thatwere isolated at 60C and 70C. Four isolates at 70C (BITSNS038, BITSNS039, BITSNS040, BITSNS041) are theproducers of thermozymes, namely amylase, xylanase, and cellulase, respectively. The highlights of the present study alsoshowed that three out of four isolates demonstrated all three enzymatic activities, i.e. amylolytic, xylanolytic and cellulolytic on agar plate assay conditions at 70C. One of the isolates, BITSNS038, was further chosen for phenotypiccharacterization as well as 16S rRNA gene sequencing and was affiliated to Geobacillus icigianus. The presence ofGeobacillus icigianus was reported first time from hot spring, Surajkund, which showed amylolytic index of 1.58,xylanolytic index of 1.5 and cellulolytic index of 2.3 based on plate assay, and amylase activity of 0.81 U/mL, xylanaseactivity of 0.72 U/mL and very less cellulase activity of 0.15 U/mL after 24 h of growth in submerged conditions. Oneisolate at 60C BITSNS024 was found to exhibit maximum amylase activity with an enzymatic index value of 3.5 and wasidentified as Anoxybacillus gonensis.