Heat Activation Characteristics of Talaromyces Ascospores

ABSTRACT: Heat activation of ascospores of 4 strains of Talaromyces was investigated. Dormancy of the ascospores was broken by heating in several buffer solutions. When the heating period was extended, emerged colonies increased at elevated temperatures and the number of colony-forming units (CFU) reached the population of the ascospores. A direct linear relationship was observed between the logarithm of CFU and the heating period at each temperature. Activation rates of the test strains were greater at higher temperatures. Activation energy values of the 4 strains, calculated on the basis of heat activation rates, ranged from 3.83 × 10⁴ to 1.39 × 10⁵ J/mol. The influence of medium on activation was studied by heating in different buffer solutions and fruit juices. The pH of buffer solutions had no effect on heat activation rates. However, activation rate was enhanced by heating in fruit juices.