Serology and yeast classification

DNA base composition of species of the genus Saccharomyces

DNA base compositions (GC content) of Saccharomyces species are reported and discussed. Several amendments of the four groups given by van der Walt are suggested, viz. the transfer of S. kluyveri to group 1, and of S. eupagycus, S. cidri, S. montanus, S. microellipsodes and S. florentinus to group 2. The synonomy of S. amurcae and S. cidri is suggested. The DNA base compositions revealed two possible pairs of sibling species: S. elegans and S. bailii, with a difference in GC content of 4.1%; S. dairensis and S. servazzii with a difference in GC content of ca. 3%. S. mrakii had a GC content of 47.3-48.5% the highest encountered in this genus and similar to that of Kluyveromyces thermotolerans.

Antigenic analysis of yeast cell-walls

Agglutination and complement fixation tests with yeast cell-walls revealed an extensive and complex pattern of cross-reactions amongst 26 species of 20 genera of yeasts. Common antigens were found in all yeast cell-walls. Ascosporogenous yeasts possessed antigens not found in the asporogenous yeasts and vice versa. Nuberical analyses of serological properties confirmed this distinction and also that little differentiation could be achieved at generic level with respect to Saccharomyces and Candida spp.