Elżbieta Johannsen

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Hybridization studies based on the prototrophic selection technique, involving the use of auxotrophic mutants of strains of all accepted species of the genus Kluyveromyces, are reported. Two main groups of mutually interfertile taxa were established within the genus. The first group comprises Kluyveromyces bulgaricus, K. cicerisporus, K. dobzhanskii, K.(More)
Five Torulopsis species, in which, characteristically, the mean molar percentage of guanine plus cytosine of the DNA bases (GC content) is above 50%, were examined to determine their cell-wall structure; the mode of bud formation; course of mitosis and their urease activity. The two urease-negative species, T. gropengiesseri (% GC 57.1) and T. silvatica (%(More)
Hybridization studies based on the prototrophic selection technique involving the use of auxotrophic mutants of seven Schwanniomyces strains are reported. Recombinant formation was not detected in any of the 87 experiments comprising both intrastrain and interstrain crosses of strains previously identified as S. alluvius, S. castellii, S. occidentalis, and(More)
The perfect state ofTorulopsis magnoliae has been identified on the basis of cytological evidence and X-ray inactivation data. This state is considered to show an affinity with the ascomycetous yeasts, but forms dangeardiens which delimit the haplophase exogenously. In accordance with established taxonomic procedure this perfect state is described as the(More)
Hybridization studies based on the use of the prototrophic selection technique were undertaken to compare interfertility and DNA-DNA reassociation as criteria for speciation purposes in the yeast genus Kluyveromyces. Degrees of DNA-DNA reassociation > 70% between strains as reported in the literature, were found to correlate with high recombination(More)
Hybridization studies based on the prototrophic selection technique, involving the use of auxotrophic mutants of strains of five accepted species of the genus Schizosaccharomyces, are reported. Intrastrain recombinants were recovered in five out of six tested parental pairs. Interstrain recombinants were recovered from crosses involving strains of S.(More)
The concept of a dangeardien is discussed in relation to the ascomycetous yeasts. In species of ascomycetous affinity the dangeardien may be expressed not only as the ascus, but also in the taxa showing an alternation of generation in the absence of an ascosporal state, as a site of reduction division. In such cases it is proposed to refer to the(More)
Hybridization studies between strains of Kluyveromyces marxianus and the remaining species of the genus involving the use of auxotrophic mutants, are reported. K. marxianus was found to be interfertile with K. bulgaricus, K. cicerisporus, K. dobzhanskii, K. drosophilarum, K. fragilis, K. lactis, K. phaseolosporus, K. vanudenii and K. wikenii. Accepting(More)
Three strains representative of two undescribed Torulopsis species, T. geochares and T. azyma, were recovered from soil and rupicolous lichen in South Africa. Descriptions of the new species are given. Ploidy determinations by X-ray inactivation showed the type strains of the two new species to be haploid. On the basis of their affinitive characteristics(More)