Screening and identification of ethanol-tolerant yeast species in spontaneous cacao (Theobroma cacao) box fermentation in Davao, Philippines

Date

4-2014

Degree

Bachelor of Science in Biology

Major Course

Major in Microbiology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Nacita B. Lantican

Abstract

The study aimed to identify ethanol-tolerant yeast species which can be included in a microbial cocktail to hasten fermentation. A total of 108 isolates were obtained from the spontaneous cacao box fermentation in Tugbok, Davao City, Philippines. They were purified and based on the combinations of morphological and cultural characteristics can be categorized into groups. Based on the banding patterns of isolates generated by microsatellite (GTG)5 fingerprinting, 38 groups were created and one representative was obtained for ethanol tolerance. Four yeast straines (colony diameter ranging from 3.40 mm to 3.70 mm) were found to be significantly more ethanol-tolerant than the rest after ethanol tolerance test on basal medium supplemented with different ethanol concentrations (6%, 8%, 10% and 12%). After Internal transcribed Spacer (ITS) PCR, sequencing of D1/D2 domain of 26S rDNA genes and phylogenetic analysis using MEGA6, two isolates established 99% match and close relationship with Pichia kudriavzevii. The other two isolates showed only 97% and 96% match and a more close relationship with each other than with the other P. kudriavzevii strains. it is possible that these other two isolates are novel straines but further sequencing and testing to determine physiological characteristics should be done to verify this assumption.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2014 B4 /B66

Document Type

Thesis

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