Isolation and characterization of the antibacterial and antifungal activity of Lactic Acid Bacteria

Research poster
Ronald Melendrez Alvarez
Rafael Jimenez-Flores
Department of Food Science and Technology

LAB in dairy products contributes to desirable sensorial characteristics. LAB strains have been reported to produce additional metabolites in addition to lactic acid. There are LAB strains with antifungal effect where their metabolites such as acetic acid share a synergistic effect with lactic acid interrupting the fungal growth. Moreover, there are compounds of bacteria that inhibit the growth of spoilage and pathogenic microorganism. This study seeks to isolate the strains from an Appenzeller cheese and evaluate its antimicrobial and antifungal properties against some pathogens (Escherichia coli, Bacillus amyloliquefaciens, Listeria innocua, Staphyloccocus epidermidis), yeast as Candida albicans and mold as Aspergillus fumigatus. The isolated LAB strains contain antimicrobial and-or antifungal activity since the original samples were kept safe during storage for a long time. The LAB were isolated from the original sample then incubated and after inoculated in broth to be proved the antimicrobial activity on TSA against pathogens and MRS + PDA for Aspergillus. The experimental design was integrated for 27 treatments, 3 repetitions and 6 different microorganisms like a block in a randomized complete block design (RCBD). The results showed that 19% of all bacteria were not lactic acid bacteria. One of the not lactic acid bacteria had antimicrobial activity against four of the five pathogens and the A. fumigatus. However, antifungal activity was found both in the LAB strains as well as the non-lactic acid bacterias. Therefore, is necessary to go belong to the experiment to find the metabolite responsible for the inhibition.