Abstract
The Saccharomyces cerevisiae wine yeast strains 71B-1122 and K1-V1116 were used to derive strains that could tolerate and produce higher ethanol yields. Respiratory-deficient mutants resistant to 500 μg/mL lycorine were isolated. Two mutants, 71B-1122 YEBr L3 and K1-V1116 YEBr L4, were shown to achieve about 10% and 18% improvement in their glucose-to-ethanol conversion efficiency compared to their respective parent strains. The K1-V1116 YEBr L4 in particular can tolerate an ethanol yield of 18.8 ± 0.8% at 3.5 weeks of fermentation and continued to consume most of the sugar until less than 1% glucose was left.
Highlights
Ethanol is a desirable fuel additive because it allows fuel to burn more cleanly and lowers greenhouse gas emissions
The expedient method of exposing the yeast cells to 25 μg/mL ethidium bromide followed by 500 μg/mL lycorine solution generated mutants from both the 71B-1122 and K1-V1116 strains that were capable of producing and tolerating higher ethanol yields than their parent strains
71B-1122 YEBr L3 and K1-V1116 YEBr L4 showed a 10% and 18% improvement in their glucoseto-ethanol conversion efficiency compared to their parent strains, respectively
Summary
Ethanol is a desirable fuel additive because it allows fuel to burn more cleanly and lowers greenhouse gas emissions. It is cost-effective to blend ethanol into gasoline in view of high crude oil prices in recent years. Most of the gasoline fuel in the United States is blended with up to 10% ethanol that is produced from the fermentation of sugar derived mostly from. A byproduct of fermentation is acetic acid, which lowers ethanol yield and is itself an undesirable component in gasoline fuel formulations. Wine and sherry wine yeasts [5,6] are generally excellent for fermenting sugar because they can produce high ethanol yield with low acetic acids
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