Differential toxinogenesis in the genus Pichia detected by an anti-yeast killer toxin monoclonal antibody.

The differential toxinogenesis of 25 isolates belonging to species of the potential yeast killer genus Pichia that were previously classified in the genus Hansenula was comparatively demonstrated by two serologic techniques (indirect immunofluorescence and double immunodiffusion) by using a monoclonal antibody against a yeast killer toxin produced by a selected strain of Pichia anomala (UCSC 25F). The killer phenotypes of the Pichia isolates were evaluated by their ability to kill each other. The results, although of insufficient taxonomic value for a reliable separation of either species or genera, attest to the genomic heterogeneity for the killer character in the genus Pichia as well as the presumptive dual killer/sensitive identity for each single isolate.