ANTIFUNGAL ACTIVITY OF MICROBIAL STRAINS ISOLATED FROM ROMANIAN SPONTANEOUSLY FERMENTED DAIRY PRODUCTS

Abstract

Phytopathogenic filamentous fungi are main producers of mycotoxins and contaminants of the grain in silos. Although several yeast and lactic acid bacteria (LAB) species are known to inhibit mycelial growth and production of mycotoxins, the diversity of fungi and the mechanisms of mycotoxin production, impose the development of new bioproducts for protection of crop plants and harvested cereals. The present work focuses on the complex characterization as biocontrol agents of 15 strains belonging to five yeast (Ogataea polymorpha, Pichia kudriavzevii, Candida parapsilosis and Saccharomyces cerevisiae) and, respectively, to eight LAB (Lactobacillus rhamnosus, L. plantarum, L. paracasei, Enterococcus faecalis) species from artisan fermented milk, sour-crème, cheese and yogurt. The mycelial growth inhibition tests against Aspergillus flavus and Aspergillus ochraceus strains, revealed values of mycelial growth inhibition index between 60 and 100%, depending on the culture media used for co-cultivation. The semi-quantitative determination of aflatoxins and ochratoxin A (Thin Layer Chromatography) proved that P. kudriavzevii L3S and SM3, respectively, L. plantarum S2B and E. faecalis U4, also interfered with mycotoxin synthesis. In conclusion, all the tested yeast and LAB strains showed complex antifungal activities representing a promising basis for the development of alternative strategies aimed to prevent fungal contamination of crops.