Strain variation in the production of Rubratoxins by penicillium rubrum stoll

A number of isolates ofPenicillium rubrum have been examined for their ability to produce the toxic metabolites Rubratoxins A and B. Some were found to produce relatively large quantities of Rubratoxin A, others to produce mainly Rubratoxin B and two strains, both isolated from samples of paper, were found not to produce any toxic metabolites under the cultural conditions used. A method for assaying Rubratoxin A in mixtures of the two toxins is described. The formal relationship of these toxins with other metabolites produced by related moulds is briefly discussed.