Optimization of cellulase production by Bacillus R101 isolated from hot spring in Tunisia

Abstract

The purpose of this work was to study the optimal cultivation conditions for cellulase production by Bacillus R101, which was isolated from Tunisia hot spring. The screening of cellulase activity from Bacillus strains was performed by agar well diffusion method on media rich in CarboxyMethyl Cellulose. Different factors (temperature, pH, fermentation time course, inoculums size, agitation, fermentation medium, different source of carbon and organic and inorganic source of nitrogen) were tested for the optimization of cellulase production and activity was assayed using DiNitroSalicylicAcide (DNSA) method. The amount of enzyme production was optimized by varying the fermentation parameters: time, pH, substrate concentration, inoculums size, temperature, fermentation media, source of carbon and source of nitrogen. The maximum CMCase production was achieved after 96 hours of incubation at temperature 55°C in a liquid medium containing (g/l): CMC, 2.0; peptone, 2.0; K2HPO4, 3.0 ; MgSO4, 1.0 ; NaCl, 0.75 and 0.1M phosphate buffer at pH 6, 5 inoculated with 10% (v/v). The best carbon source, organic nitrogen source and inorganic nitrogen source were found to be maltose, malt extract and ammonium sulphate respectively. When different nitrogen sources were tested, the results showed that enzyme activities were higher with organic than inorganic nitrogen. Results indicated that optimal fermentation conditions play a key role in the maximum production of cellulase from Bacillus R101. Optimization of process parameters is necessary to enhance the enzyme production in fermentation system.