Cyclopiazonic acid production by Penicillium camemberti Thom and natural occurrence of this mycotoxin in cheese.

Every Penicillium camemberti strain freshly isolated from 20 commercial cheese brands produced cyclopiazonic acid in two culture media at 25, 13, and 4 degrees C; the toxin yield was greatly dependent on the strain and environmental parameters (medium, temperature, and incubation time). The toxigenic ability appeared as a log-normal distribution. This mycotoxin was found in the crust (0.05 to 0.1 microgram/g in three samples, 0.1 to 0.2 microgram/g in five samples, and 0.4, 1, and 1.5 microgram/g in three other samples) but not in the inner part. When its acute toxicity is considered, doses eventually ingested by consumers are very low (lower than 4 microgram). Means for prevention are discussed. A highly toxigenic strength and rate appear to be necessary features leading to natural contamination in cheeses. The distribution of toxigenic ability makes possible without delay a choice of weakly toxic strains.