title: Construction of an industrial brewing yeast strain to manufacture beer with low caloric content and improved flavor.
abstract: In this study, the problems of high caloric content, increased maturation time and off-flavors in commercial beer manufacture arising from residual sugar, diacetyl, and acetaldehyde levels were addressed. A recombinant industrial brewing yeast strain (TQ1) was generated from T1 [Lipomyces starkeyi dextranase gene (LSD1) introduced, alpha-acetohydroxyacid synthase gene (ILV2) disrupted] by introducing Saccharomyces cerevisiae glucoamylase (SGA1) and a strong promoter PGK1 while disrupting the genes coding alcohol dehydrogenase (ADH2). The highest glucoamylase activity for TQ1 was 93.26 U/ml compared with host strain T1 (12.36 U/ml) and wild-type industrial yeast strain YSF5 (10.39 U/ml), respectively. European Brewery Convention (EBC) tube fermentation tests comparing the fermentation broths of TQ1 with T1 and YSF5 showed that the real extract were reduced by 15.79% and 22.47%; the main residual maltotriose concentration were reduced by 13.75% and 18.82%; the caloric content were reduced by 27.18 and 35.39 calories per 12 oz. Due to the disruption of ADH2 gene in TQ1, the off-flavor acetaldehyde concentration in the fermentation broth were 9.43% and 13.28% respectively lower than that of T1 and YSF5. No heterologous DNA sequences or drug-resistance genes were introduced into TQ1. So, the gene manipulations in this work properly solved the addressed problems in commercial beer manufacture.
authors.affiliation: Graduate University of Chinese Academy of Sciences, Beijing 100049, China, BBEL, Washington State University, Pullman, WA 99163, USA.
authors.forename: Jin-Jing
authors.initials: JJ
authors.lastname: Wang
authors.forename: Zhao-Yue
authors.initials: ZY
authors.lastname: Wang
authors.forename: Xi-Feng
authors.initials: XF
authors.lastname: Liu
authors.forename: Xue-Na
authors.initials: XN
authors.lastname: Guo
authors.forename: Xiu-Ping
authors.initials: XP
authors.lastname: He
authors.forename: Pierre Christian
authors.initials: PC
authors.lastname: Wensel
authors.forename: Bo-Run
authors.initials: BR
authors.lastname: Zhang
mesh_terms: D000426:Alcohol Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D001515:Beer / Q000382:microbiology*; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D005818:Genetic Engineering / Q000379:methods*; D005087:Glucan 1,4-alpha-Glucosidase / Q000235:genetics / Q000378:metabolism*; D007218:Industrial Microbiology / Q000379:methods*; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D011995:Recombination, Genetic / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D013649:Taste
chemical_list: D004271:DNA, Fungal; D000426:Alcohol Dehydrogenase; D005087:Glucan 1,4-alpha-Glucosidase