Inhibitory activity of cell--free extracts of lactobacillus plantarum against streptoccus agalactiae

Date of Completion


Document Type


Degree Name

Bachelor of Science in Medical Laboratory Science


Lactobacillus plantarum, Streptoccus agalactiae


The study used disk diffusion method. An aliquot of 20 UL supernatant applied on a sterilized cellusose disk measuring 6 mm placed on a brain heart infusion (BHI) agar inoculated with streptococcus agalactiae. The plates were incubated at 37°C for 24 hours and measured the diameters of the zone of inhibition. The results of the study showed that the diameter of the zone of inhibition of the cell free extract has a mean of 13.62a that according the Zone Diameter Interpretative Standard (ZDIS) shows that streptococcus agalactiae is resistant to the cell free extract. The metabolite on the cell free extract were proteinaceous in nature and the peptide is glygcosylated that is stable in acidic pH and thermo stable at 65°C. The study concluded that there was significant different between the antimicrobial activity of cell-free extract of L. plantarum and commercially available antimicrobial drug against S. agalactiae. The study revealed that the metabolite present in cell-free extract of L. plantarum is stable at an acidic PH and loses its activity as the pH increases.

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