Cellulolytic, amylolytic and xylanolytic potential of thermophilic isolates of Surajkund hot spring.

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