Cellulase production by thermophilic Bacillus sp. SMIA-2 and its detergent compatibility

Abstract

Background: This paper reports the production of cellulase by thermophilic Bacillus sp. SMIA-2 using sugarcane bagasse and corn steep liquor as substrates. Some biochemical properties of the enzyme were also assessed for the purposes of exploiting its potential in the detergent industry, as well as other suitable applications. Results: Bacillus sp. produced cellulases when cultivated at 50°C in liquid cultures containing sugarcane bagasse and corn steep liquor. Maximum avicelase (0.83 U mL-1) and CMCase (0.29 U mL-1) activities were reached in 120 h and 168 h of culturing time, respectively. The avicelase and CMCase presented an optimum activity at pH of 7.5 and 8.0, respectively. The maximum stability of avicelase and CMCase was observed at a pH range between 6.5-8.0 and 7.0-9.0 respectively, where they retained more than 70% of their maximum activities after incubation at room temperature for 3 h. The optimum temperature of avicelase and CMCase was 70°C, and both enzymes remained 100% stable until the treatment at 60°C for 1 h. Bacillus sp. cultures also released proteases into the culture medium, but the cellulases were resistant to protease digestion. The compatibility of cellulases varied with each laundry detergent tested, being more stable in the presence of Ultra Biz® and less with Ariel®. In addition, the enzyme was stable in sodium dodecyl sulfate and RENEX-95, and was inhibited by TritonX-100 and H2O2. Conclusions: The properties presented by Bacillus sp. SMIA-2 suggest that this organism might become a potential source of lignocellulose-degrading enzymes for industrial applications such as in the detergent industry.