Cellulase production by co-culture of Bacillus licheniformis and B. paralicheniformis over monocultures on microcrystalline cellulose and chicken manure-supplemented rice bran media

Abstract

Single cultures and co-cultures of Bacillus licheniformis and Bacillus paralicheniformis isolated from compost were evaluated for their carboxymethyl cellulase (CMCase) and filter paperase (FPase) production potential. Using a medium supplemented with microcrystalline cellulose (MCC), in the co-culture, CMCase and FPase activities increased 8.87- and 2.28-fold and 10.15- and 3.20-fold over B. licheniformis and B. paralicheniformis monocultures, respectively. The synergistic behavior of the two isolates might be due to the consumption of hydrolysis product (glucose, cellobiose) by one or both of the isolates, which improved their metabolic performance for cellulase secretion. Optimal conditions for cellulase production by this co-culture were a temperature of 45 °C, and pH 7 at 180 rpm in a medium containing rice bran at 1% (w/v) and chicken manure as nitrogen supplement at 2% (w/v). The maximum CMCase and FPase produced under the above conditions were 79.8 U/mL and 12.5 U/mL, respectively. This corresponds to 257.4- and 59.5-fold enhancement in CMCase and FPase activity, respectively, over B. licheniformis monoculture, and 306.9- and 83.3-fold increase with respect to the B. paralicheniformis monoculture. These results indicate that improved cellulase production can be achieved through co-culture and chicken manure nitrogen-supplement.