Efficient production of ethanol from raw starch by a mated diploid Saccharomyces cerevisiae with integrated α-amylase and glucoamylase genes

• Published in: Enzyme and microbial technology Vol. 44; no. 5; pp. 344 - 349
• Main Authors: Yamada, Ryosuke, Bito, Yohei, Adachi, Takashi, Tanaka, Tsutomu, Ogino, Chiaki, Fukuda, Hideki, Kondo, Akihiko
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 06.05.2009; Elsevier
• Subjects: Biological and medical sciences; Biotechnology; Diploid yeast; Ethanol fermentation; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; Raw starch; Diploid yeast; Ethanol fermentation; Raw starch; Ascomycota; Glucan 1,4-α-glucosidase; Yeast; Ethanol; Enzyme; Starch; Fermentation; Fungi; Glycosylases; Gene; Glycosidases; Production; Hydrolases; α-Amylase; Saccharomyces cerevisiae
• ISSN: 0141-0229; 1879-0909
• DOI: 10.1016/j.enzmictec.2009.01.001

The goal of this research was to construct a stable and efficient process for the production of ethanol from raw starch, using a recombinant Saccharomyces cerevisiae, which is productive even under conditions such as non-selection or long-term operation. Three recombinant yeast strains were used, two haploid strains (MT8-1SS and NBRC1440SS) and one diploid strain (MN8140SS). The recombinant strains were constructed by integrating the glucoamylase gene from Rhizopus oryzae fused with the 3′-half of the α-agglutinin gene as the anchor protein, and the α-amylase gene from Streptococcus bovis, respectively, into their chromosomal DNA by homologous recombination. The diploid strain MN8140SS was constructed by mating these opposite types of integrant haploid strains in order to enhance the expression of integrated amylase genes. The diploid strain had the highest ethanol productivity and reusability during fermentation from raw starch. Moreover, the ethanol production rate of the integrant diploid strain was maintained when batch fermentation was repeated three times (0.67, 0.60, and 0.67 g/l/h in each batch). These results clearly show that a diploid strain developed by mating two integrant haploid strains is useful for the establishment of an efficient ethanol production process.