Saccharification of delignified rice straw by Fusarium oxysporum for ethanol production by Saccharomyces cerevisiae

Abstract

In the present work, a preliminary test proved that there was no contradiction between using Saccharomyces cerevisiae as single culture or mixed with Fusarium oxysporum in fermenting glucose to ethanol. Rice Straw was subjected to delignification by alkaline/hypochlorite method. Delignified rice straw (RS) and carboxy methyl cellulose (CMC) individually were used in bioconversion process for ethanol production. Fusarium oxysporum performed fermentation with and without aeration, achieving ethanol production of 0.8µl/ml and 2.9µl/ml, respectively, proving the importance of air absence in this process. The CMC and RS were applied in a submerged culture to give maximum cellulases activity of 0.444U and 1.474U after 8 days, respectively. In order to apply consolidated bioprocessing, saccharification of either CMC or RS by F. oxysporum was applied in a single submerged culture giving maximum saccharification efficiency of 16.8% and 16% after 7 and 11 days, respectively. In the same submerged culture, Saccharomyces cerevisiae was used to ferment the released sugar under no aeration achieving ethanol production of 6.1% and 3.878% (v/v) corresponding to fermentation efficiency of 42.4% and 34.4%, respectively.