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Intracellular ethanol accumulation in Saccharomyces cerevisiae during fermentation.
T D'Amore1, C J Panchal, G G Stewart
1Production Research Department, Labatt Brewing Company Limited, London, Ontario, Canada.
Applied and Environmental Microbiology
|January 1, 1988
Summary
Yeast cells initially accumulate ethanol intracellularly during fermentation. Nutrient limitation, not ethanol levels, limits growth and fermentation at high osmotic pressures.
Area of Science:
- Microbiology
- Biochemistry
- Yeast Fermentation
Background:
- Ethanol accumulation is a key factor influencing yeast fermentation.
- Understanding intracellular vs. extracellular ethanol dynamics is crucial for optimizing industrial yeast processes.
- Osmotic stress impacts yeast physiology and fermentation efficiency.
Purpose of the Study:
- To investigate the dynamics of intracellular and extracellular ethanol accumulation in Saccharomyces cerevisiae under varying osmotic pressures.
- To determine the role of nutrient availability in mitigating the negative effects of osmotic stress on yeast growth and fermentation.
Main Methods:
- Monitoring intracellular and extracellular ethanol concentrations over time during fermentation.
- Assessing yeast cell growth and fermentation activity under different osmotic conditions.
- Evaluating the impact of nutrient supplementation on yeast performance under osmotic stress.
Main Results:
- Intracellular ethanol accumulation was observed early in fermentation (3h), with levels equalizing extracellularly by 12h.
- Increased osmotic pressure led to a higher intracellular/extracellular ethanol ratio at 3h and reduced yeast growth and fermentation.
- Nutrient supplementation enhanced growth and fermentation, ensuring complete glucose utilization despite unaltered intracellular ethanol levels.
Conclusions:
- Nutrient limitation, rather than intracellular ethanol concentration, is the primary cause of reduced yeast growth and fermentation under high osmotic pressure.
- Optimizing nutrient availability can enhance yeast resilience and performance in osmotically challenging environments.
- Saccharomyces cerevisiae exhibits complex responses to osmotic stress, involving both ethanol partitioning and nutrient management.