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Evaluation of bacterial contamination in a fed-batch alcoholic fermentation process
1Departamento de Ciências Biológicas, Faculdade de Ciências e Letras, UNESP, C.P. 335-CEP, 19800-000, Assis, SP, Brazil.
World Journal of Microbiology & Biotechnology
|January 15, 2014
Summary
Lactic acid produced by Lactobacillus fermentum inhibits baker's yeast fermentation. High acidity levels negatively impact yeast viability and reduce alcohol production efficiency in fed-batch processes.
Area of Science:
- Biotechnology
- Industrial Microbiology
- Fermentation Science
Background:
- Commercial baker's yeast is crucial for alcoholic fermentation.
- Fed-batch processes with cell recycling enhance yeast fermentation efficiency.
- Contamination by other microorganisms can impact fermentation outcomes.
Purpose of the Study:
- To investigate the inhibitory effects of Lactobacillus fermentum on baker's yeast in a fed-batch fermentation.
- To determine the impact of increasing lactic acid concentration on yeast viability and fermentation performance.
Main Methods:
- Fed-batch fermentation using commercial baker's yeast and high-test molasses.
- Inoculation with Lactobacillus fermentum CCT 1407 to assess inhibition.
- Monitoring of total acidity, yeast bud formation, viability, and alcoholic efficiency.
Main Results:
- Lactobacillus fermentum strongly inhibited yeast fermentation after a few recycles.
- Total acidity exceeding 4.8 g/l interfered with yeast bud formation and viability.
- Acidity above 6.0 g/l significantly decreased alcoholic efficiency.
Conclusions:
- Lactobacillus fermentum poses a significant challenge to baker's yeast fed-batch fermentation.
- Lactic acid accumulation is the primary factor causing inhibition.
- Controlling bacterial contamination is essential for optimizing industrial yeast fermentation processes.
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