Improvement in the thermotolerance and ethanol yield of Saccharomyces cerevisiae HBY3 via UV mutagenesis.

Date

4-2011

Degree

Bachelor of Science in Biology

Major Course

Major in Cell Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Cheryl A. Agdaca

Co-adviser

Jessica F. Simbahan

Abstract

Ultraviolet (UV) irradiation was used to obtain mutant strains of the industrial yeast strain Saccharomyces cerevisiae HBY3, a strain developed at UPLB-BIOTECH. Protoplasts of the cells, isolated through incubation in 0.02 mg/mL zymolyase 100T solution for 180 minutes, were irradiated with UV (260nm) at 5, 10 and 15 minutes at a distance of 20 cm. Cells were regenerated in YEPD agar with 80% sorbitol. Optimum growth condition for the irradiated strains was at 30 *C without ethanol in the medium. All strains were not able to grow at 37°C with 10% (v/v) ethanol in the medium. Five mutant strains with higher viability at arc than the parental strain (2030) were selected for alcohol production using molasses as substrate. These strains were designated as mut 1. mut2, mut3, mut4 and mut5. Cell areas of mut4 and mut5 were significantly larger than 2030 by 25% and 12%, respectively, while area of mut2 was smaller than 2030 by 18%. Differences in ethanol production among the strains were observed at 42°C. Mut3 showed lower ethanol yield than 2030 at 24 hours of fermentation. Mut5 showed 9.6% and 12% higher alcohol yield than 2030 after 24 hours and 48 hours of fermentation, respectively. This suggests that UV irradiation may result in reduced or improved fermentation abilities in yeast. With further tests on its fermentation characteristics, mut5 has potential for industrial ethanol production.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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