Ethanol production using nuclear petite yeast mutants

• Published in: Applied microbiology and biotechnology Vol. 49; no. 5; pp. 511 - 516
• Main Authors: Hutter, A, Oliver, S.G
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.05.1998; Springer Nature B.V
• Subjects: Bacteria; Batch culture; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Cell culture; Drug tolerance; Dry cells; Ethanol; Ethanol - metabolism; Ethanol - pharmacology; ethanol production; Fermentation; Fundamental and applied biological sciences. Psychology; Gene disruption; gene targeting; Genetics; metabolism; Mission oriented research; mitochondria; Mutants; pharmacology; Polymerase chain reaction; Saccharomyces cerevisiae; Saccharomyces cerevisiae - metabolism; Toxins; Yeast; Yeasts; Yeast; Ethanol; Fungi; Toxin; Mitochondria; Sensitivity resistance; Pasteur effect; Microorganism culture; Ascomycetes; Mutation; Saccharomyces cerevisiae; Thallophyta; Cell respiration
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s002530051206

Two respiratory-deficient nuclear petites, FY23 delta pet191 and FY23 delta cox5a, of the yeast Saccharomyces cerevisiae were generated using polymerase-chain-reaction-mediated gene disruption, and their respective ethanol tolerance and productivity assessed and compared to those of the parental grande, FY23WT, and a mitochondrial petite, FY23 rho 0. Batch culture studies demonstrated that the parental strain was the most tolerant to exogenously added ethanol with an inhibition constant. K(i), of 2.3% (w/v) and a specific rate of ethanol production, q(p), of 0.90 g ethanol g dry cells-1 h-1. FY23 rho 0 was the most sensitive to ethanol, exhibiting a K(i) of 1.71% (w/v) and q(p) of 0.87 g ethanol g dry cells-1 h-1. Analyses of the ethanol tolerance of the nuclear petites demonstrate that functional mitochondria are essential for maintaining tolerance to the toxin with the 100% respiratory-deficient nuclear petite, FY23 delta pet191, having a K(i) of 2.14% (w/v) and the 85% respiratory-deficient FY23 delta cox5a, having a K(i) of 1.94% (w/v). The retention of ethanol tolerance in the nuclear petites as compared to that of FY23 rho 0 is mirrored by the ethanol productivities of these nuclear mutants, being respectively 43% and 30% higher than that of the respiratory-sufficient parent strain. This demonstrates that, because of their respiratory deficiency, the nuclear petites are not subject to the Pasteur effect and so exhibit higher rates of fermentation.