Production , Purification and Optimization of Cellulase by Bacillus licheniformis HI-08 Isolated from the Hindgut of Wood-feeding Termite

Bacteria are potential microorganisms involved in enzymatic hydrolysis of agricultural wastes by producing cellulases and other valuable chemicals. Different ionic solvents at different pH and temperature are also involved in the pretreatment of agricultural wastes to enhance the saccharification by cellulases. However, the remaining and conditioning of pretreatment buffers strongly inhibit the cellulase activity. In view of this, a symbiotic cellulolytic strain was isolated from the gut of building infesting termite Heterotermes indicola for the production of ionic-solvent tolerant cellulase. After screening by Congo red, strain HI-08 was identified as Bacillus licheniformis using 16S rDNA sequence analysis. It was accounted for maximum cellulase production on 2% sugarcane bagasse (1156 U/mL). The crude cellulase was purified by (NH4)2SO4 precipitation, affinity and size exclusion chromatography, with 12.02 purification fold and 32.33% overall recovery. Approximately 55 kDa molecular weight of gel-purified cellulase was revealed by SDS-PAGE analysis. The optimum temperature and pH for maximum cellulase activity was determined as 45°C and 7.0, respectively. Kinetic analysis of purified cellulase showed the Km and Vmax be 2.24 mg/mL and 454.05 μg/mL/min, respectively. Statistical optimization using RSM indicated that sugarcane bagasse was most useful agricultural waste for cellulase production, which proved its candidature in industrial bio ventures. © 2018 Friends Science Publishers