Evaluation of performance of different surface-engineered yeast strains for direct ethanol production from raw starch

• Published in: Applied microbiology and biotechnology Vol. 70; no. 5; pp. 573 - 579
• Main Authors: Khaw, Teik Seong, Katakura, Yoshio, Koh, Jun, Kondo, Akihiko, Ueda, Mitsuyoshi, Shioya, Suteaki
• Format: Journal Article
• Language: English
• Published: Berlin Berlin/Heidelberg : Springer-Verlag 01-05-2006; Springer; Springer Nature B.V
• Subjects: alpha-Amylases - genetics; alpha-Amylases - metabolism; Biological and medical sciences; Biotechnology; Ethanol; Ethanol - metabolism; Fermentation; Fundamental and applied biological sciences. Psychology; Gene Expression; Genetic Engineering; Saccharomyces cerevisiae; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Starch; Starch - metabolism; Yeast; Yeasts; Performance evaluation; Glucan 1,4-α-glucosidase; Yeast; Ethanol; Enzyme; Starch; Fermentation; Cell surface; Genetically modified microorganism; Fungi; Glycosidases; Production; Hydrolases; Ascomycetes; Saccharomyces cerevisiae; Thallophyta
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-005-0101-z

Four types of cell-surface-engineered yeast Saccharomyces cerevisiae displaying glucoamylase, namely, systems A, B, C, and D, were constructed to evaluate their performance in direct ethanol fermentation from raw corn starch. Systems A and B were glucoamylase-displaying nonflocculent yeast (YF237) types that secrete α-amylase into the culture medium and codisplay α-amylase on the cell surface, respectively. Systems C and D were flocculent yeast counterparts (YF207) for systems A and B, respectively. In batch fermentations, the specific ethanol production rates of systems A, B, C, and D were 0.18, 0.06, 0.06, and 0.04 g (g cell)-¹ h-¹, respectively. In repeated fermentations, the specific ethanol production rate of system A decreased with the number of repetitions, whereas, that of system B was maintained. In all systems, the rate-limiting step was the conversion of starch to oligosaccharide because oligosaccharide and glucose were not accumulated throughout the fermentations.