Antimicrobial effects of probiotic bacteria against selected species of yeasts and moulds in cheese-based dips

Abstract

The antimicrobial properties of selected probiotic bacteria against Aspergillus niger, Penicillium roqueforti, Fusarium spp., Candida albicans and Saccharomyces cerevisiae were examined. Well diffusion and spot and streak methods showed strong inhibition effect of probiotic bacteria and their metabolites against moulds and minimal effect against yeasts. Among the moulds species tested, the inhibitory effect was strongest against Fusarium spp., moderate against Penicillium roqueforti and minimal against A. niger. All strains of Lactobacillus rhamnosus and L. paracasei subsp. paracasei showed maximum inhibitory effect. When probiotic bacteria and yeasts and moulds were co-cultured in broth media, strains of L. rhamnosus showed maximum inhibitory effect, whereas L. paracasei subsp. paracasei, L. acidophilus, Bifidobacterium animalis and Propionibacterium showed moderate inhibitory effect against C. albicans. Saccharomyces cerevisiae was minimally controlled by probiotic bacteria. Pre-grown probiotic bacterial culture metabolites controlled yeasts and moulds more effectively than their freeze-dried or frozen forms. Adding metabolites of probiotic bacteria (5% w/w) showed an effective control against A. niger, Fusarium spp. and C. albicans during the shelf life of 10 weeks at 4 �C and no colonies of yeasts and moulds were formed on the surface of the dip