Isolation and identification of acetic acid bacteria from cacao (Theobroma cacao) box fermentation

Date

3-2014

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

Seeds of the cacao tree, Theobroma cacao, undergo a long process to become chocolates and cocoa products. Spontaneous fermentation, driven by the activity of microorganisms, is the first step in chocolate development. A microbial succession takes place during fermentation, wherein yeasts predominate first, followed by lactic acid bacteria. Acetic acid bacteria proliferate towards the end of fermentation. This study focused on the isolation and identification of putative acetic acid bacteria from cacao fermentation samples taken from two fermentation plants in Davao City, Philippines. A total of 89 isolates were obtained. From these, 26 gram negative acid producing isolates were selected for further screening. Repetitive sequence-based polymerase chain reaction using the microsatellite primer (GTG)5 resulted to 18 distinct banding patters. One representative isolate for each banding pattern was identified using 16S rDNA analysis. All isolates share 99-100% similarities with known sequences on GenBank. The isolates were found to be highly similar to five species of acetic acid bacteria, namely, Acetobacter cerevisiae strain T0-PCP23, Acetobacter pasteurianus strain G17-11, Gluconobacter frateurii strain SL13-8, Gluconobacter oxydans strain JM2, and Gluconobacter sp. UFLA CHE3.13. Some sequences were highly similar to lactic acid bacteria species also involved in cacao fermentation, such as Fructobacillus tropaeoli, Lactobacillus sp., Lactococcus sp., and Leuconostoc sp. A phylogenetic tree was constructed to illustrate the inferred relationships of the isolates.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2014 B4 /C54

Document Type

Thesis

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