ANTIFUNGAL ACTION OF LACTIC ACID BACTERIA ISOLATED FROM PLANT MATERIALS AGAINST MYCOTOXIGENIC FUNGI

The contamination of food and feed by mycotoxigenic fungi that belong to genera Aspergillus, Alternaria, Fusarium and Penicillium poses significant risks for animal and human health. The mycotoxins (aflatoxins, trichothecenes, ochratoxins, fumonisin etc) produced by such spoilage fungi can be carcinogenic, hepatotoxic, teratogenic or immunosuppressing (Logrieco et al., 2003; Atanda et al., 2013). The limitation of the mycotoxin contamination of food and feed could be achieved by specific methods that inhibit the fungal growth. Several approaches are described by now to avoid the accumulation of mycotoxins, directed towards: prevention of contamination; decontamination of mycotoxin-containing food and feed; and inhibition or absorption of mycotoxin content of consumed food into the digestive tract (Juodeikiene et al., 2012). The use of biological control microorganisms (bacteria, yeasts or fungi) to inhibit the growth of mycotoxin producing fungi and/or degrade the mycotoxins is an important strategy for prevention/decontamination of products (Tsitsigiannis et al., 2012). The aim of this work was the screening of new lactic acid bacteria (LAB) strains isolated from plant materials or some Romanian traditional foods for antifungal action againstplant pathogenic fungi and mycotoxin producing Aspergillus strains. 123 strains of LAB were examined for anti-Aspergillus action and 24 out of them (more than 21%) exhibit strong inhibitory activity against the growth of A.flavus, A.ochraceus and A.niger strains after 3 days of incubation. For most of the LAB strains the inhibitory action was maintained even after 14 days of incubation. The principal antifungal compound is represented by lactic acid, quantified by HPLC. Important damages of the fungal hyphae were observed at microscopic level (fragmentation, loss of the cellular content, twisting of hyphae or apical swelling). 17 new isolate of Aspergillus spp. were obtained and their ability to produce mycotoxin was evaluated by qualitative and quantitative methods. Four of them were used for interactions with LAB: strong and stable inhibition was obtained with the LAB strains designated as 35, 58 and 26. The results suggest that selected LAB could be used for fungal growth inhibition and possible for mycotoxin content reduction.