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 H
2O
2.
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.