Isolation and Characterization of Cellulase-producing Bacteria from Sugar Industry Waste

Cellulases are inducible enzymes that are synthesized by a large number of microorganisms during their growth on cellulosic materials. This study focuses on the isolation and screening of cellulase-producing bacteria from sugar industry waste (molasses) and characterization by morphological and biochemical analysis. Further, purification of cellulase was carried by ammonium sulfate precipitation and followed by column chromatography and molecular weight determined by SDS-PAGE. The isolated bacterial strains were grown on carboxymethyl cellulose (CMC) agar plate at various optimum conditions like pH, temperature, incubation period, carbon and nitrogen sources and substrate concentration. Three isolated strains showed clear hydrolyzing zone on agar plates containing CMC agar after Congo-red staining were identified as cellulase-producing bacteria. Based on cultural, morphological, and biochemical characteristics, the isolated strains were identified as Paenibacillus sp., Aeromonas sp., and Bacillus sp. Among the isolated strains, Paenibacillus sp. showed the capability for highest cellulase production (0.89 µmol ml-1 min-1) at optimal pH 7.0 and 40°C temperature on 24 hour of the incubation period at 1% CMC substrate concentration and was selected for further cellulase purification. In the final step of cellulase purification, the specific activity, purification fold and recovery were 1720 U/mg, 9.74 and 35.6%, respectively. The molecular weight of the purified enzyme was determined 66.9 kDa and the enzyme showed a high specificity to CMC substrate. The bacterial strains present in molasses have the potential for cellulase production. Substrate specificity of the purified cellulase indicates it to be an endo-β-1, 4-glucanase. The cellulase produced from the selected strain may benefit for industrial application.