Characterization of mitochondrial DNA in various Candida species: isolation, restriction endonuclease analysis, size, and base composition.

A practical and effective method for the extraction of mitochondrial DNA from Candida species was developed. Zymolyase was used to induce yeast protoplasts, and mitochondrial DNA was extracted from DNase I-treated mitochondrial preparations. Restriction endonuclease analyses of mitochondrial DNAs from 19 isolates representing seven species of Candida (C. albicans, C. kefyr, C. lusitaniae, C. maltosa, C. parapsilosis, C. shehatae, and C. tropicalis) and Lodderomyces elongisporus revealed different cleavage patterns that appeared to be specific for the species. Few common restriction fragments were evident. The genome sizes of the mitochondrial DNAs ranged from 26.4 to 51.4 kilobase pairs, and the guanine-plus-cytosine contents ranged from 20.7 to 36.8 mol%. There was no correlation between the base compositions of nuclear and mitochondrial DNAs. Eight isolates of C. parapsilosis, including the type culture, and an ascosporogenous strain of L. elongisporus, which was once proposed as the teleomorph of C. parapsilosis, had similar mitochondrial DNA molecular sizes (30.2 and 28.8 kilobase pairs); however, restriction endonuclease patterns of these organisms were distinct. These data provide additional support for discrimination of these two species. The results of our experiments demonstrate that mitochondrial DNA analyses may provide useful criteria for the differentiation of yeast species.