Evaluation of the temperature of tolerance level of sachharomyces serevisae through acclimatization

• Main Authors: Montejo, Fernando Manuel Antonio A., Mendoza, Lean Angelo L.
• Format: text
• Published: Animo Repository 2014
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/10721
• Institution: De La Salle University

This research involves the fermentation of molasses by Saccharomyces cerevisiae. The temperature tolerance of S. cerevisiae was evaluated in terms of its biomass and ethanol producing capability in batch fermentation through the process of acclimatization. The acclimatized yeast was fermented in three different temperatures (300C, 350C, and 400C) and two different initial total sugar concentration (200 g/L, 250 g/L). Three runs from the 250 g/L initial total sugar medium were compared with the runs from thermal shock stage while the six runs were used to determine the best parameters in terms of biomass and ethanol production rate and ethanol yield. It was found out that the acclimatized yeast had lower growth in the growth media compared to the thermally shocked yeast. However, in the fermentation of molasses, biomass and ethanol production was higher for the acclimatized yeast. Highest biomass and ethanol production for both thermally shocked and acclimatized yeasts were obtained at 400C with 3.9032 g/L biomass and 15 g/L ethanol for the thermal shocked yeast and 4.0302 g/L biomass and 20 g/L ethanol for the acclimatized yeast, respectively. For the acclimatized yeast, the best parameters in terms of biomass production rate was fermentation at 400C and 250 g/L initial total sugar with a biomass production rate of 0.144 g/L h. Temperature was the only significant factor affecting biomass production rate. On the other hand, ethanol production rate was highest at 0.7692 g/L h when the temperature was 40oC and total sugar was 250 g/L, however, total sugar concentration and temperature were not significant factors. For ethanol yield, the highest was 10.061 g ethanol/g biomass obtained at 30oC and 250 g/L total sugar, and both factors were significant. The projected best conditions based on the main effects plot are: 200 g/L total sugar and 40oC for biomass production, 250 g/L total sugar and 30oC for both ethanol production and ethanol yield. Initial kinetic study showed that the experimental data did not fit Monod equation.