Growth of Aspergillus ochraceus, A-carbonarius and A-niger on culture media at different water activities and temperatures

Abstract

The objective of this paper was to determine the influence of three culture media with different water activities, times of incubation and temperatures on the growth of A. ochraceus, A. carbonarius and A. niger. Spores of A. ochraceus, A. carbonarius and A. niger were inoculated onto three culture media: Czapeck Yeast extract Agar (CYA), Dichloran 18% Glycerol Agar (DG18) and Malt Yeast extract 40% Glucose Agar (MY40G). The plates were incubated at five different temperatures (8, 25, 30, 35 and 41 degrees C). The growth of fungi was evaluated every 24h, measuring the colony diameter (mm). None of the species grew at 8 degrees C in any culture media. For A. carbonarius, 30 degrees C was the best temperature for growth while for A. niger temperatures above 30 degrees C were better in all culture media. A. ochraceus presented good growth at 25 and 30 degrees C in all culture media, while at 35 degrees C, growth was slower, especially on CYA. At 41 degrees C, A. ochraceus did not grow in any culture media and A. carbonarius was significantly inhibited. A. niger grew at 41 degrees C and was shown to be the most xerophilic fungi when compared to A. carbonarius and A. ochraceus.361242