Methods of numerical taxonomy for various genera of yeasts

Nucleotide sequence of the Schizosaccharomyces japonicus var. versatilis ribosomal RNA gene cluster and its phylogenetic implications

Fission yeasts form a small but heterogeneous group of ascomycetes and it is still unclear whether they should be subdivided into three genera (Schizosaccharomyces, Octosporomyces, Hasegawaea) or remain a single genus (Schizosaccharomyces). In order to decide whether a new genus Hasegawaea should be established for the species Schizosaccharomyces japonicus and Schizosaccharomyces versatilis, we have characterized the entire rDNA cluster in Schizosaccharomyces japonicus var. versatilis and compared it with the homologous region from Schizosaccharomyces pombe and with complete rRNA gene sequences from other yeast genera. From a phage genomic library a recombinant lambda phage containing the entire rDNA repeat unit was isolated. In this paper we report the primary sequence of the 18s, 5.8s and 25s rRNA coding regions. The S. japonicus var. versatilis rRNA genes are 1823 (18s), 158 (5.8s) and 3422 (25s) nucleotides long. The two sequences of the larger rRNA genes exhibit 95.7% (18s) and 93% (25s) similarity with the homologous genes from S. pombe. The differences between the rRNA genes of S. japonicus and S. pombe, however, are much smaller than the intrageneric differences within the rDNA sequences of other yeast genera. Therefore, subdivision of fission yeasts into the genera Schizosaccharomyces and Hasegawaea does not to seem to be justified.

[Taxonomical investigations in sexual strains of Rhodotorula glutinis (Fres.) Harrison, Rh. aurantiaca (Saito) Lodder and Rh. rubra (Demme) Lodder (author's transl)]

Several strains of Rhodotorula were crossed with the strains IFO 0559a and IFO 0880alpha of Rhodotorula glutinis. We found nine new sexual Rhodotorula strains, belongong to the species Rh. glutinis, Rh. aurantiaca and Rh. rubra. 22 combinations, whose physiological and biochemical qualities were found out, followed from crossings of all sexual strains. The cell walls of some selected mycel combinations contained a pore in the center. Resting spores and life cycles of all combinations correspond to Rhodosporidium toruloides Banno. Results and taxonomical problems are being discussed.

Taxonomical examination and characterization of a methanol-utilizing yeast

The morphological, cultural, and physiological characteristics are described of a yeast, LI70, which uses methanol as its source of energy and carbon; these characteristics have made it possible to identify the strain as Candida boidinii Ramirez. The identification was confirmed by a DNA-DNA genetic homology of 99.43% with the type strain of C. boidinii. Strain LI70 is not pathogenic.