Two New and Closely Related Heterothallic Species, Pichia amylophila and Pichia mississippiensis: Characterization by Hybridization and Deoxyribonucleic Acid Reassociation

Two new species of the yeast genus Pichia were isolated from frass obtained from loblolly pines growing in Mississippi. The new taxa, designated Pichia amylophila and Pichia mississippiensis, are heterothallic, and Candida obtusa var. arabinosa proved to be a haploid member of the latter species. The species show interspecific mating, but ascospores from the crosses are infertile. The nuclear deoxyribonucleic acids from the species differ by 2 mol% in guanine plus cytosine content and exhibit low (25%) base sequence complementarity. Deoxyribonucleic acid relatedness was determined spectrophotometrically, and the methodology is given in detail.