Use of conventional taxonomy, electrophoretic karyotyping and DNA-DNA hybridization for the classification of fermentative apiculate yeasts.

A taxonomic study was conducted that considered strains of the genera Hanseniaspora/Kloeckera held in the Industrial Yeasts Collection (DBVPG) of the Dipartimento di Biologia Vegetale of the Università di Perugia, Italy. Standard phenotypic as well as molecular criteria were considered in a effort to revisit the classification of these strains, some of which have been in the collection for about 50 years. Results of salient physiological tests showed that some of the DBVPG and type strains could not be identified by current taxonomic keys. Electrophoretic karyotypes were identical for some species, with the type strains of the seven accepted species showing only five distinct chromosomal patterns. DNA-DNA hybridization analyses, using a non-radioactive dot-blot technique, allowed for the distinction of taxa. The taxonomic implications of these results are discussed.

Synonomy of the yeast genera Saccharomyces Meyen ex Hansen and Pachytichospora van der Walt.

The type strains and other strains of the phenotypically similar taxa Saccharomyces castelli Capriotti, Saccharomyces dairensis Naganishi, and Pachytichospora transvaalensis van der Walt were studied by comparing the ascospore morphologies of these organisms by examining ultrathin sections by transmission electron microscopy. The results of this study and another investigation of DNA base sequence homology demonstrated that the monotypic genus Pachytichospora van der Walt is invalid. We propose that the species Saccharomyces transvaalensis van der Walt should be reinstated.