INFLUENCE OF TEMPERATURE, PH AND WATER ACTIVITY ON IN-VITRO INHIBITION OF PENICILLIUM-GLABRUM (WEHMER) WESTLING BY YEASTS

Four different yeast species (Metschnikowia pulcherrima, Saccharomycop sis vini, Kluyveromyces marxianus, Cryptococcus albidus), isolated fro m surface of grapes, were evaluated for biocontrol potential against P enicillium glabrum. In order to investigate the influence of temperatu re, pH, water activity and yeast cell concentration on Penicillium gla brum inhibition, the individual effects and the interaction of these f actors were analyzed by means of a Central Composite Design (CCD). All yeast species tested showed antagonistic effects which were more pron ounced at high cell concentrations. The other variables affected the a ntagonistic effect differentially depending on the yeast species. Resu lts of the experimental design showed that the selective success of a competitive microflora is under environmental control; moreover, when microbial cells are subjected to multiple factors, the effects and the reciprocal interactions of the individual variables cannot be indepen dently evaluated.