title: Development of redox potential-controlled schemes for very-high-gravity ethanol fermentation.
abstract: Fermentation redox potential reflects the momentary physiological status of organisms. Controlling redox potential can modulate the redistribution of intracellular metabolic flux to favor the formation of the desired metabolite. Accordingly, we have developed three redox potential-controlled schemes to maximize their effects on the very-high-gravity (VHG) ethanol fermentation. They are aeration-controlled scheme (ACS), glucose-controlled feeding scheme (GCFS), and combined chemostat and aeration-controlled scheme (CCACS). These schemes can maintain fermentation redox potential at a prescribed level (i.e., -50, -100, and -150 mV) by supplementing sterile air, fresh glucose media, or a combination of sterile air and fresh glucose media into a fermenter to counteract the decline of redox potential due to yeast growth. When ACS was employed, the fermentation efficiency at -150 mV is superior to the other two redox potential levels especially when the initial glucose concentration is higher than 250 g/l. The redox potential-controlled period for ACS, GCFS, and CCACS at -150 mV under the same 200 g glucose/l condition was 2.5, 21.7 and 64.6h and the corresponding fermentation efficiency was 85.9,89.3 and 92.7%, respectively.
authors.affiliation: School of Life Science and Biotechnology, Dalian University of Technology, Dalian, Liaoning 116023, China.
authors.forename: Chen-Guang
authors.initials: CG
authors.lastname: Liu
authors.forename: Yen-Han
authors.initials: YH
authors.lastname: Lin
authors.forename: Feng-Wu
authors.initials: FW
authors.lastname: Bai
mesh_terms: D000332:Aerobiosis / Q000187:drug effects; D001709:Biotechnology / Q000379:methods*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000187:drug effects / Q000502:physiology*; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D018471:Hypergravity; D050296:Microbial Viability / Q000187:drug effects; D010084:Oxidation-Reduction / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D000431:Ethanol; D005947:Glucose