Bioprocessing of Lignocellulosic Biomass for Production of Bioethanol using Thermotolerant Aspergillus fumigatus under Solid State Fermentation Conditions

Screening of cellulolytic activity by ten fungal isolates recovered from soil and agricultural wastes indicated that Aspergillus fumigatus showed the highest cellulolytic activity, under solid-state fermentation (SSF) using rice straw as substrate. Optimization of fermentation conditions showed that highest cellulolytic enzymes production on 4* day at pH 5.5 and at 40°C. The production of enzymes was reached its maximal value at 5.0 g/flask of rice straw. Avicellase, endoglucanase and CMCase productivity were highly increased by addition of L-asparagine, NH4Cl and NaNO3, respectively as N-sources to the fermentation medium. Maximum activities of avicellase and endoglucanase were recorded at inoculum size of 2.5 mL, while maximum activity of CMCase was detected at inoculum size of 0.5 mL. The influence of various physico-chemical factors "incubation period, temperature, pH and substrate concentration" on enzyme activity was also investigated. The half life time of avicellase, endoglucanase and CMCase at 60°C were 67.8, 79.1 and 96.5 min, respectively. Rice straw hydrolysate obtained through enzymatic hydrolysis of rice straw was used as a substrate for bioethanol production. Maximum ethanol production by Saccharomyces cereviseae using dilute acid pretreated rice straw hydrolysate with initial soluble sugar 4.1055±0.0146% was recorded after 48 h of fermentation (2.26424±0.0206%). © 2010 Asian Network for Scientific Information.