title: Optimization of enzymatic hydrolysis of pretreated rice straw and ethanol production.
abstract: Cellulase, Tween 80, and β-glucosidase loading were studied and optimized by response surface methodology to improve saccharification. Microwave alkali-pretreated rice straw used as substrate for onsite enzyme production by Aspergillus heteromorphus and Trichoderma reesei. The highest enzymatic hydrolysis (84%) was obtained from rice straw at crude enzyme loading of 10 FPU/gds of cellulase, 0.15% Tween 80, and 100 international unit/g dry solids of β-glucosidase activities. Enzymatic hydrolyzate of pretreated rice straw was used for ethanol production by Saccharomyces cerevisiae, Scheffersomyces stipitis, and by co-culture of both. The yield of ethanol was 0.50, 0.47, and 0.48 g(p)/g(s) by S. cerevisiae, S. stipitis, and by co-culture, respectively, using pretreated rice straw hydrolyzate. The co-culture of S. cerevisiae and S. stipitis produced 25% more ethanol than S. cerevisiae alone and 31% more ethanol than S. stipitis alone. During anaerobic fermentation 65.08, 36.45, and 50.31 μmol/ml CO(2) released by S. cerevisiae, S. stipitis, and by co-culture, respectively. The data indicated that saccharification efficiency using optimized crude enzyme cocktail was good, and enzymatic hydrolyzate could be fermented to produce ethanol.
authors.affiliation: Department of Environmental Science and Engineering, Guru Jambheshwar University of Science and Technology, Hisar, Haryana, India. anitasaharan@gmail.com
authors.forename: Anita
authors.initials: A
authors.lastname: Singh
authors.forename: Narsi R
authors.initials: NR
authors.lastname: Bishnoi
mesh_terms: D001230:Aspergillus / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D006868:Hydrolysis; D012275:Oryza / Q000378:metabolism* / Q000382:microbiology*; D018547:Plant Stems / Q000378:metabolism / Q000382:microbiology; D004718:Saccharomycetales / Q000378:metabolism*; D014242:Trichoderma / Q000378:metabolism*
chemical_list: D000431:Ethanol