title: Enhanced production of bioethanol from waste of beer fermentation broth at high temperature through consecutive batch strategy by simultaneous saccharification and fermentation.
abstract: Malt hydrolyzing enzymes and yeast glycolytic and fermentation enzymes in the waste from beer fermentation broth (WBFB) were identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). A new 'one-pot consecutive batch strategy' was developed for efficient bio-ethanol production by simultaneous saccharification and fermentation (SSF) using WBFB without additional enzymes, microbial cells, or carbohydrates. Bio-ethanol production was conducted in batches using WBFB supernatant in the first phase at 25-67°C and 50rpm, followed by the addition of 3% WBFB solid residue to the existing culture broth in the second phase at 67°C. The ethanol production increased from 50 to 102.5g/L when bare supernatant was used in the first phase, and then to 219g ethanol/L in the second phase. The amount of ethanol obtained using this strategy was almost equal to that obtained using the original WBFB containing 25% solid residue at 33°C, and more than double that obtained when bare supernatant was used. Microscopic and gel electrophoresis studies revealed yeast cell wall degradation and secretion of cellular material into the surrounding medium. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) supported the existence of enzymes in WBFB involved in bioethanol production at elevated temperatures. The results of this study will provide insight for the development of new strategies for biofuel production.
authors.affiliation: Department of Chemical Engineering, Kyungpook National University, Daegu 702-701, South Korea.
authors.forename: Waleed Ahmad
authors.initials: WA
authors.lastname: Khattak
authors.forename: Taous
authors.initials: T
authors.lastname: Khan
authors.forename: Jung Hwan
authors.initials: JH
authors.lastname: Ha
authors.forename: Mazhar
authors.initials: M
authors.lastname: Ul-Islam
authors.forename: Min-Kyung
authors.initials: MK
authors.lastname: Kang
authors.forename: Joong Kon
authors.initials: JK
authors.lastname: Park
mesh_terms: D001515:Beer; D057005:Bioengineering; D056804:Biofuels; D019149:Bioreactors; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D006358:Hot Temperature; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D014866:Waste Products / Q000032:analysis
chemical_list: D056804:Biofuels; D014866:Waste Products; D000431:Ethanol
keywords: Bio-ethanol; Cellular matrix; Glycolytic and fermentation enzymes; One-pot consecutive batch strategy; Simultaneous saccharification and fermentation; Waste from beer fermentation broth