Biotyping of micelial fungus cultures by the killer system.

Based on the occurrence of the yeast killer phenomenon in hyphomycetes, the toxic effect of 37 selected killer yeasts was studied on eleven strains of Pseudallescheria boydii, six strains of Aspergillus niger, 18 strains of Penicillium camemberti and nine strains of Sporothrix schenckii. The demonstration of different biotypes within the species of P. boydii and P. camemberti proves that the killer system also is a practical and effective method for epidemiological studies among hyphomycetes. Based on the system used, it was not possible to observe markedly different biotypes among the A. niger and S. schenckii strains studied. The first evidence that an isolated, concentrated (50X) and partially purified yeast killer toxin may display a lethal activity against mycelial fungus cultures is also given in this paper.