Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XIX
Written by Adrian MATEI, Călina Petruța CORNEA
Various spoilage fungi that contaminate fruits, vegetables and other food commodities produce economic losses as well as harmful effects on human and animal health caused by ingestion of mycotoxins The public concern about the use of chemical fungicides during cultivation and storage of fruits and vegetable determined the search for new strains of lactic acid bacteria (LAB) able to control the fungal growth of mycotoxigenic species. The effect of 8 LAB strains have been assayed on the growth of Penicillium expansum isolated from infected apples. Interaction between LAB strains and selected spoilage fungi was tested by overlay assay method. Discrete spots of liquid cultures of tested LAB strains were placed on MRS agar and after incubation, overlaid with soft PDA containing fungal propagules. Data concerning the evolution of the diameters of clear visible inhibition zones of fungal growth around the LAB strain spots were monitored for 10 days. A number of 5 strains have shown antifungal activity with clear inhibition zone developed at 5 days, the effect of 2 strains being sustained until the 10th day of monitoring. P. expansum spores were cultivated with 3 efficient LAB strains on PD liquid medium and monitored for 17 days. The inhibition of spore forming lasted for 2 strains until the end of monitoring period and for the other strain until the end of the first week. Completely sporulated mycelium with powdery aspect was evidenced in control flask with pure culture of P. expansum after 5 days. Probably chemical interactions appeared between fungus and LAB strains that changed the color of culture media towards reddish-brown comparatively to control. The results could be used in biotechnological methods for the control of spoilage fungi with application in fruits preservation.
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antifungal activity
