Genome comparisons in the yeastlike fungal genus Galactomyces Redhead et Malloch

The G+C contents of the DNAs of 41 strains belonging to the genus Galactomyces Redhead et Malloch were determined by the thermal denaturation method. Melting profiles revealed that the DNAs of these strains are heterogeneous. Four groups were recognized on the basis of this heterogeneity. However, DNA similarity values, which were calculated by using DNA-DNA reassociation kinetics, revealed that the strains could be divided into six subgroups. Strains belonging to the same subgroup exhibited high levels of DNA similarity (84 to 100%). The members of two subgroups, corresponding to Galactomyces citri-aurantii and Galactomyces reessii, exhibited low levels of DNA similarity with the members of the other subgroups (20 to 27%). The members of the four remaining subgroups, which contained only strains previously identified as Galactomyces geotrichum, exhibited intermediate levels of reassociation (41 to 59%). Some combinations of phenotypic characteristics correlated with the subgroups; a key based on phenotypic characteristics that can be used to distinguish the subgroups is presented.