- Volume 36, Issue 1, 1986

Natural isolates of Kluyveromyces from a variety of habitats were compared on the basis of seven isoenzyme patterns. Some strains of Candida considered to be Kluyveromyces anamorphs, as well as one strain each of Candida sake, Saccharomyces cerevisiae, and Pichia fluxuum, were also examined. The isoenzyme patterns readily substantiated the relationships between the anamorphs and their putative teleomorphs and the nonmember status of strains not belonging to the genus. A multivariate analysis of the electrophoretic patterns indicated that isolates belonging to the Kluyveromyces lactis and Kluyveromyces marxianus deoxyribonucleic acid reassociation groups are not phenotypically continuous with one another or with the former species Kluyveromyces dobzhanskii, and thus we propose to reinstate these taxa as separate species. Taxa previously described as Kluyveromyces thermotolerans and Kluyveromyces waltii also appeared to constitute reproductively isolated natural populations. When the results of isoenzyme electrophoresis were compared with deoxyribonucleic acid reassociation data and with mating compatibility patterns determined by other workers, we found that deoxyribonucleic acid relatedness gives a more accurate view of relationships among Kluyveromyces species.