Studies on Aspergillus flavus - II. Responses of germinating conidia to single and combined treatments of gamma radiation and heat

Abstract

The response of germinating conidia of Aspergillus flavus (aflatoxin producing) and A. flavus oryzae (non-toxigenic) to heat, radiation and combination treatments has been studied. Germinating conidia of both strains of fungi were more susceptible to heat injury than non-germinating conidia and the susceptibility was enhanced with increased incubation period before treatment. Susceptibility to radiation injury, however, increased only for a short period followed by development of resistance. The germinating stage which was highly resistant to radiation was very sensitive to heat (50°/5 min). With combinations of heat and radiation, an irradiation-heat sequence was more effective than the reverse sequence for all germinating stages of A. flavus (toxigenic). However, in the case of the non-toxigenic strain, irrespective of germinating stage, irradiation of conidia before heating proved to be less effective than the reverse sequence.