ECOPHYSIOLOGICAL CHARACTERIZATION OF COMMON FOOD-BORNE FUNGI IN RELATION TO PH AND WATER ACTIVITY UNDER VARIOUS ATMOSPHERIC COMPOSITIONS

The combined effects of pH, water activity (a(w)), oxygen (O-2) and ca rbon dioxide (CO2) levels on growth and sporulation of 10 common food- borne fungi were studied. The use of a multivariate statistical method (PLS) for the analysis of data showed that the fungi could be grouped according to their physiological response to changes in the four test ed factors. Carbon dioxide, a(w) and pH were found to be the most sign ificant factors describing differences and similarities among the fung i. Maximal inhibitory effect of elevated levels of CO2 (5-25%) and dec reased a(w) (0.99-0.95) varied among the 10 species from 6 to 77% and from 52 to 100%, respectively. Sporulation of the fungi was sensitive to all tested factors. Furthermore, interaction of CO2 and a(w) displa yed a significant effect on sporulation. It was shown that different f ungal species associated with the same ecosystem responded similarly t o changes in the tested factors. Thus, fungi which are not phylogeneti cally related may be physiologically related or show a common strategy of life.