Evaluation of yeast strains for biomass production from cane molasses


Ma. Lourdes T. Escarrilla, Ma. Florencia T. Logrono and Teresita O. Macuro


Abstract

Sugarcane product diversification and by-products utilization are now serious alternatives or options for the rationalization and improvement of the sugarcane industry. Within the program of product diversification is the integration of cattle and swine production with the sugarcane farm and/or sugar factory. Cattle feed ingredients are largely imported. The production of feed yeast from cane molasses to augment domestic feed ingredients could be a viable industry.
The Sugar and Sugar By-Products Research Division of SRA conducted a project on the production of yeast from cane molasses for animal feed. Five yeast strains were found to have significant differences in their capacities to produce biomass from cane molasses.
Ethanol production was higher in the high sugar medium than in the low at 30oC. Lambanog yeast, Saccharomyces cerevisiae, and Candida hypolytica produced more ethanol at 38oC from the low sugar medium (7.16%, 7.56%, and 6.58%, respectively). All yeast strains except Rhodotorula rubra were observed to be thermotolerant strains. Lambanog yeast was exceptionally thermotolerant as it yielded 3.18% (w/v) ethanol at 42oC. The specific ethanol productivities of Lambanog and S. cerevisiae were highest at 38oC from molasses at 5% total sugar content.
Lambanog produced highest biomass consistently from 16 to 32 hours fermentation at 38oC although not significantly different from the other strains. After 36 hours, C. lypolytica and C. tropicales produced more biomass than Lambanog and S. cerevisiae. Lambanog yeast was observed to be most alcohol tolerant, followed by C. lipolytica.
C. lipolytica and C. tropicales, considered as feed yeast strains, offer possibilities as ethanol-producing strains, as well as biomass producers; C. lipolytica was observed to better maintain cell growth at high sugar medium than Lambanog yeast. In low sugar medium at high temperature (38oC), C. lipolytica can still maintain cell growth and produce alcohol as much as S. cerevisiae and Lambanog yeast. Lambanog on the other hand offers possibilities as yeast source in the primary process, as well as by-product process in yeast production.

http://www.sra.gov.ph/abstract/

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