Date

4-2010

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Ida F. Dalmacio

Co-adviser

Francisco B. Elegado

Abstract

One hundred (100) presumptive Enterococcus spp. were isolated from fecal samples of four types of birds in three areas in Laguna. These isolates were partially characterized using morphological, biochemical, and physiological tests to further establish their membership in the genus Enterococcus. All the fecal isolates were found to have characteristics typical for enterococci. These isolates were then screened for antimicrobial activity against selected spoilage and pathogenic bacteria using agar-stab, spot on lawn, agar-well, and cylinder cup methods. During primary screening using agar stab method, all isolates were tested to have inhibitory activity against all the indicator strains and 45 of these fecal bacteria produced distinct inhibition zones. Using spot on lawn method, isolates PPC1, PD3, LD1, SM5, and SC7 showed the highest zones of inhibition (> 20mm). The antagonistic activity was attributed to the production of bacteriocin and bacteriocin-like substances. No inhibitory activity was observed during secondary screening using agar-well method due to the insufficient amount of cell-free extracts used. However, inhibition zones were observed on some indicator strains in cell-free and cell-incorporated extracts using cylinder cup method. Inhibition which was observed during the secondary screening can be attributed to the production of organic acid (lactic acid) and bacteriocins; the latter being triggered by cell density or cell-to-cell communication. Altogether, fecal enterococci isolated from bird droppings in three areas in Laguna were shown to have antimicrobial activity against gram-positive and gram- negative indicator bacteria due to elaboration of acid but more importantly due to the production of bacteriocin and bacteriocin-like substances.

Language

English

LC Subject

Microbiology

Document Type

Thesis

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