title: Development of flocculent Saccharomyces cerevisiae strain GYK-10 for the selective fermentation of glucose/fructose in sugar mills.
abstract: Advances in glucose/fructose-selective ethanol production have successfully enhanced raw sugar extraction from sugarcane juice by converting inhibitory substances (i.e., glucose/fructose) into ethanol, which is removed by subsequent operations in cane sugar mills. However, the commercial implementation of this breakthrough process in existing cane sugar mills requires a yeast strain that (i) can be used in food production processes, (ii) exhibits stable saccharometabolic selectivity, and (iii) can be easily separated from the saccharide solution. In this study, we developed a suitable saccharometabolism-selective and flocculent strain, Saccharomyces cerevisiae GYK-10. We obtained a suitable yeast strain for selective fermentation in cane sugar mills using a yeast mating system. First, we crossed a haploid strain defective in sucrose utilization with a flocculent haploid strain. Next, we performed tetrad dissection of the resultant hybrid diploid strain and selected GYK-10 from various segregants by investigating the sucrose assimilation and flocculation capacity phenotypes. Ten consecutive fermentation tests of the GYK-10 strain using a bench-scale fermentor confirmed its suitability for the implementation of practical selective fermentation in a commercial sugar mill. The strain exhibited complete saccharometabolic selectivity and sustained flocculation, where it maintained a high ethanol yield and conversion rate throughout the test.
authors.affiliation: Department of Brewing Microbiology, Asahi Breweries Ltd., 1-1-21 Midori, Moriya, Ibaraki 302-0106, Japan. Electronic address: taku.kato@asahibeer.co.jp.
authors.forename: Taku
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Bioethanol Production Technology, Asahi Group Holdings Ltd., 1-1-21 Midori, Moriya, Ibaraki 302-0106, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ohara
authors.affiliation: Department of Chemical Engineering, Tohoku University, 6-6-07 Aramaki-aza Aoba, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Fukushima
authors.affiliation: Department of Bioethanol Production Technology, Asahi Group Holdings Ltd., 1-1-21 Midori, Moriya, Ibaraki 302-0106, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Sugimoto
authors.affiliation: Department of Bioethanol Production Technology, Asahi Group Holdings Ltd., 1-1-21 Midori, Moriya, Ibaraki 302-0106, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Masuda
authors.affiliation: Department of Bioethanol Production Technology, Asahi Group Holdings Ltd., 1-1-21 Midori, Moriya, Ibaraki 302-0106, Japan.
authors.forename: Takaomi
authors.initials: T
authors.lastname: Yasuhara
authors.affiliation: Department of Brewing Microbiology, Asahi Breweries Ltd., 1-1-21 Midori, Moriya, Ibaraki 302-0106, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yamagishi
mesh_terms: D019149:Bioreactors; D004171:Diploidy; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005427:Flocculation; D019649:Food Industry; D005632:Fructose / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006238:Haploidy; D012441:Saccharomyces cerevisiae / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D031786:Saccharum / Q000737:chemistry*; D013395:Sucrose / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D005632:Fructose; D000431:Ethanol; D013395:Sucrose; D005947:Glucose
keywords: Ethanol; Inversion process; Reducing sugar; Selective fermentation; Yeast