Deoxyribonucleic Acid Base Composition and Deoxyribonucleic Acid/Deoxyribonucleic Acid Hybrid Formation in Psychrophobic and Related Yeasts

The deoxyribonucleic acid (DNA) base composition of several strains of the psychrophobic species Saccharomyces telluris, Torulopsis pintolopesii, T. bouina, and Candida slooffii was found to be similar, DNA/DNA hybridization experiments by means of the nitrocellulose filter technique revealed high degrees of homology between the nuclear DNAs of all four species. On the basis of these findings, T. bovina is considered to be a synonym of T. pintolopesii; C. slooffii, which has certain distinct and reproducible properties, was reclassified as T. pintolopesii var. slooffii. Saccharomycopsis guttulata has been retained as a separate species because its guanine plus cytosine value is higher than that of the four species mentioned above and it has other distinct properties. The nonpsychrophobic species Torulopsis glabrata was included for comparison. The guanosine plus cytosine content of its DNA was approximately 7% higher than that of T. pintolopesii.