Monday, April 29, 2013
Exhibit Hall
Stirred tank (STR) and pneumatic bioreactors can be used for cellulase production. Even though STR have been widely used for enzyme production, pneumatic bubble column (BC) bioreactors present many advantages including low power consumption associated with high oxygen mass transfer. Cellulase production can be conducted under solid-state fermentation (SSF) or submerged fermentation (SmF). Here, a non-conventional sequential solid-state and submerged cultivation method is being proposed, which combines the advantages of SmF and SSF. In an attempt to compare endoglucanase production in three-phase cultivations, experiments were conducted in Erlenmeyer flasks (EF), STR and BC type bioreactors. The pre-culture initiated as SSF using sugarcane bagasse as substrate for 24 h. After that, a liquid nutrient medium containing 1 % (w/v) of sugarcane bagasse was added for transition from SSF to SmF. Maximum values for endoglucanase production were 1,181±141, 1,052±34, and 716±90 IU.L-1 in STR, EF and BC, respectively. Although higher enzyme production were obtained using STR and EF in comparison to BC, both STR and BC bioreactors showed similar results in terms of volumetric endoglucanase productivity (57±13 and 46±3 IU.L-1.h-1, respectively), which is 3-fold higher than in EF. Since volumetric productivities were similar for both bioreactor types, the choice of STR or BC for cellulase production can rely on the specific operational advantages of each type of bioreactor.