Production of PR toxin and roquefortine by Penicillium roqueforti isolates from Cabrales blue cheese
1985
PR toxin production in yeast extract-sucrose broth by 33 Penicillium roqueforti isolates from Cabrales blue cheese was quantified by a disc assay technique with Bacillus megaterium NRRL B-1368 as the test organism. Isolates from the interior of the cheese reached an average production of 1,89 mg PR toxin/100 ml, whereas the mean level of isolates from the surface was 1.64 mg/100 ml. Roquefortine production in the same broth by these isolates was quantified by a similar technique, with Bacillus stearothermophilus DSM 22 as the test organism. Mean production of roquefortine was 0.18 mg/100 ml for P. roqueforti isolates from the interior and 0.09 mg/100 ml for isolates from the surface of the cheese. If lactose or sodium lactate replaced sucrose in the growth medium, levels of both toxins decreased considerably. The identity of PR toxin and roquefortine in crude extracts was confirmed by thin-layer chromatography.
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