Growth kinetics of cultures from single spores of Aspergillus flavus and Fusarium verticillioides on yellow dent corn meal

A dilution protocol originally developed for the isolation of single bacterial cells was modified to suite the specificities of fungal growth. The modified protocol was used to study the growth kinetics of single spores of Aspergillus flavus and Fusarium verticillioides on yellow dent corn meal. Both aw and temperature significantly influenced the distributions of the colony growth rates and lag phases and the rate at which individual spores of both isolates completed the lag period. An interaction between aw and temperature was noted on the spread of the distributions of these growth parameters. The histograms of the single spore colony growth rates and lag phases generally became wider the more compromising the conditions for growth became, indicating a greater variation in growth ability at these conditions. The rate at which the single spores passed through the lag phases generally decreased with decrease in temperature and/or aw, with an interaction again noted between these two factors on the rate. These results show the potential range and variability in growth of individual fungal spores at the lowest inoculum level possible.