Incidence and detection of thermotolerant and thermophilic fungi from maize with particular reference to Thermoascus species.

A number of thermotolerant and thermophilic fungi were isolated from shipments of food-aid grain, and from large bag stacks of maize stored in sub-Saharan Africa. Thermotolerant fungi included Aspergillus candidus, A. fumigatus, A. flavus and Paecilomyces varioti; thermophilic fungi included Thermomyces lanuginosus, Rhizomucor pusillus, Thermoascus aurantiacus and T. crustaceous. Temperature profiles for Thermoascus spp. indicated that isolates of T. aurantiacus grew up to 60 degrees C, and T. crustaceous to 55 degrees C, whereas Paecilomyces could not grow above 50 degrees C. Thermoascus species isolated from grains conformed to published morphological descriptions. Problems associated with the detection and interpretation of fungal spoilage in relation to heat-damaged grain are discussed.