Antagonistic activities against selected pathogens of a bacteriocin-producing lactic acid bacteria isolated from Balao-balao, a fermented rice-shrimp mixture

• Published in: Food Research (Online) Vol. 8; no. 5; pp. 430 - 437
• Main Authors: Young, J.M., Galon, B.T., Simora, R.M.
• Format: Journal Article
• Language: English
• Published: 30.10.2024
• ISSN: 2550-2166; 2550-2166
• DOI: 10.26656/fr.2017.8(5).149

Lactic acid bacteria from a fermented rice-shrimp mixture traditionally known in the Philippines as Balao-balao were isolated in the present study. Screening of lactic acidproducing strains revealed that ten isolates showed promising inhibitory activities against test microorganisms namely Staphylococcus aureus BIOTECH 1634, Escherichia coli BIOTECH 1582, Bacillus subtilis BIOTECH 1679 and Vibrio harveyi SEAFDEC 010. Of interest was isolate PL12, a bacteriocin-producing strain which showed the highest inhibitory activity against the pathogens tested. Isolate PL12 was identified as Pediococcus pentosaceus (GenBank accession number MF353992) with 100% similarity by 16S rDNA sequence analyses. Excluding the effects of organic acids and hydrogen peroxide, the cell-free supernatant (CFS) of PL12 isolate exhibited strong antagonistic activities against test pathogens in an agar well diffusion assay. These results confirmed the isolate’s proteinaceous nature and are indicative of typical characteristics of bacteriocins. To further concentrate the proteins present in the CFS, ammonium sulfate precipitation followed by column purification (Sep-Pak C18 cartridge column) was performed. Positive antagonism of PL12 bacteriocin was observed in both Gram-positive and Gram-negative bacteria tested. The highest inhibitory activity was found against E. coli in every purification step. These results suggested that bacteriocin-producing PL12 isolate can be a promising preservative in the food industry and as probiotics in aquaculture since it possesses antagonistic activities against V. harveyi.