Cellulases (EC 3.2.1.4) are complex hydrolases mainly comprising of exoglucanase, endoglucanase and ß-glucosidase that act synergistically to breakdown cellulosic substrates. This study aims to produce cellulase from a thermophilic bacterium at optimum conditions of temperature, incubation period and pH while the culture is provided with most suitable C-source and N-source at optimum levels required for growth and enzyme production. A thermophilic cellulolytic bacterium was isolated from hot-spring water and the isolate was identified morphologically as well as by molecular techniques. Optimization of cellulase production was done by monitoring the cellulase production on different temperature, pH and incubation time and by varying media constituents like C- and N-sources. During each optimization, the previous optimum parameter obtained was used on the subsequent optimization of next parameter. The organism was found to be gram positive, thin, motile rod with terminal endospores and growing optimally between 55oC to 65oC and pH 5.5 to 6.5, which on phylogenetic analysis based on partial 16S rDNA gene sequence comparison showed high levels of similarity with Geobacillus thermoleovorans. Optimum production of cellulase was observed on incubation at 55oC for 18 hours in a medium containing Carboxymethyl cellulose (CMC) and yeast extract as C- and N-sources. Since, bacterial enzymes are expressed at relatively low levels, the optimization of different parameters is therefore important to augment the level of enzyme production.
