Monday, April 29, 2013
Exhibit Hall
The development of bioprocesses for cellulase production is needed in order to reduce lignocellulosic ethanol costs. Among cellulase producer microorganisms, Trichoderma and Aspergillus are the most studied strains. The conventional cultivation methods for enzyme production are solid state fermentation (SSF) and submerged fermentation (SmF). Here, a new cultivation method is being proposed by using a sequential solid-state and submerged cultivation (SF), which allows a combination of the advantages of SSF and SmF. The aim of this study was to compare endoglucanase production by Trichoderma reesei and Aspergillus niger in SmF and SF cultivations. In SF cultivations, a first step of pre-culture in SSF using sugarcane bagasse was conducted for 24 h. After that, a liquid nutrient medium was added for transition from SSF to SmF. Conventional SmF cultivations were also conducted for both strains. Enzyme production in the presence of 1 % (w/v) of sugarcane bagasse was conducted for 72 h. The peak of endoglucanase production by T. reesei using in natura sugarcane bagasse was 669±35 and 159±6 IU.L-1 under SF and SmF, respectively. For A. niger, the activities were 1,052±34 and 824±44 IU.L-1. When steam-exploded sugarcane bagasse was used in SF, the activities were higher, 945±66 and 1,727±19 IU.L-1 for T. reesei and A. niger, respectively. It was observed a significant increase in endoglucanase production using pretreated sugarcane bagasse. Thus, SF cultivation showed as a promising method for cellulase production by both strains, resulting in productivity values up to 2-folder higher than SmF.