Characterization and Optimization of an Anti‐Aeromonas Bacteriocin Produced by Lactococcus lactis Isolated from Hukuti Maas, an Indigenous Fermented Fish Product

Lactococcus lactis ssp. lactis HKBT‐9 strain isolated from hukuti maas, produced a bacteriocin active against foodborne pathogens with specificity toward Aeromonas spp. The bacteriocin produced was sensitive to proteolytic enzymes, stable between pH 2.0 and 10.0, and was thermoresistant (15 min at 121C). Proteinase K, pepsin, ethylenediaminetetraacetic acid and urea strongly inhibited bacteriocin production indicating that the active component of bacteriocin was proteinaceous. Among detergents, sodium dodecyl sulphate, Tween 80 and Tween 20 enhanced bacteriocin activity, which may be due to nondenaturation or its association with other molecules, with a stabilizing effect on bacteriocin activity. Enzymes like α‐amylase; DNase and RNase showed slightly increased bacteriocin activity. Maximum activity (2,844 arbitrary units [AU]/mL) against Aeromonas hydrophila was observed and remained for at least 24 h. Optimization using response surface methodology resulted in increased bacteriocin production of 3,591.09 AU/mL at 37.36C, pH 6.63 and inoculum size of 1.53 optical density. PRACTICAL APPLICATIONS: Bacteriocins of lactic acid bacteria have been found to kill or inhibit the growth of foodborne pathogens and spoilage microflora, and hence, can be used as natural preservatives in the production of foods with enhanced shelf life and/or safety. With the emergence of antibiotic‐resistant gram‐positive pathogenic bacteria, the possibility of bacteriocins as supplements or replacements for antibiotics for therapeutic use is also being considered. Of all the antimicrobial peptides, very few have been used as preservatives in the food industry and/or as antibiotic substances in medicine. In the present study, characterization and optimization of an anti‐Aeromonas bacteriocin produced by Lactococcus lactis isolated from hukuti maas was attempted, which could be used a potential food biopreservative.