Improvement in ethanol production using respiratory deficient phenotype of a wild type yeast Saccharomyces cerevisiae ITV-01

An osmotolerant low pH resistant wild type Saccharomyces cerevisiae ITV-01 yeast was employed to obtain respiratory deficient (RD) strains in order to improve ethanol production. The respiratory deficient phenotype was induced by exposure to chemical agents such as ethidium bromide, rhodamine, and ethanol. Isolation with physical agents such as temperature and UV radiation (254 nm) exposures was evaluated. 104 strains were tested. Selection criterion was based on increasing ethanol yield. All RD strains had higher ethanol yields (from 0.41 to 0.50 gg−1, corresponding 82–98% theoretical yields) than the wild type yeast (0.40 gg−1). Temperature and ethanol mutant agents caused a reversible phenotype in every case. Screening showed that S. cerevisiae ITV-01 RD-B14 (lacking cytochrome c), obtained using bromide ethidium, had the highest alcoholic fermentation efficiency (95%) and 97% viability under the tested conditions (150 gL−1 glucose, pH 3.5). The respiratory deficient mutation is of interest as a tool for improving ethanol production.

► Wild type S. cerevisiae ITV-01 was employed to obtain respiratory deficient (DR).
► All DR strains had higher ethanol yields than the wild type yeast.
► DR-B14 obtained using bromide ethidium, had 95% alcoholic fermentation efficiency.
► The respiratory deficient mutation is a tool for improving the ethanol production.