Heat Resistant Moulds Research Articles

Enumeration of Byssochlamys and Other Heat-Resistant Molds

Methods for the detection of low numbers of heat-resistant molds on fruits were studied by using cultures of Byssochlamys and a number of unidentified mold isolates. Ascospore dormancy had a marked effect on viable recoveries, and the medium in which ascospores were heated influenced activation rates. Best results were obtained when fruit homogenates were heated for 60 min at 70 C in Concord grape juice, followed by culturing on acidified Potato Dextrose Agar.

Enumeration of Byssochlamys and Other Heat-Resistant Molds 1

Methods for the detection of low numbers of heat-resistant molds on fruits were studied by using cultures of Byssochlamys and a number of unidentified mold isolates. Ascospore dormancy had a marked effect on viable recoveries, and the medium in which ascospores were heated influenced activation rates. Best results were obtained when fruit homogenates were heated for 60 min at 70 C in Concord grape juice, followed by culturing on acidified Potato Dextrose Agar.

A Selective Method for Cultivating Heat Resistant Moulds, particularly those of the Genus Byssochlamys, and their Presence in Dutch Soil

Summary: Heat resistant moulds of the genera Byssochlamys, Aspergillus, Penicillium and Paecilomyces can be cultivated selectively in the presence of Bacillus spp. when at least 10 p/m of chloramphenicol or chlortetracycline is added to the growth medium. The inhibitory agents sulphafurazole, penicillin, streptomycin, oxytetracycline and furazolidone, do not give completely selective and optimal growth of these moulds. Selective cultivation of heat resistant moulds from 200 samples of Dutch soil showed that Byssochlamys nivea occurs more frequently than was expected, whereas Byss. fulva occurs by way of exception. Other heat resistant moulds observed in soil are, in order of frequency, species of the genera Aspergillus, Paecilomyces and Penicillium.

Occurrence of a Heat-resistant Species of Aspergillus in Canned Strawberries

Two earlier records exist of heat-resistant moulds causing spoilage in canned and bottled fruits: Byssochlamys fulva1,2, which produces ascospores capable of withstanding relatively high temperatures (94° C for 2 min), and a species of Penicillium the sclerotia of which are reported3 to survive exposure to 93.3° C for 9 min. We wish to recordl the isolation from canned strawberries of a fungus showing an even greater degree of heat resistance than these.