Pichia heedii, a New Species of Yeast Indigenous to Necrotic Cacti in the North American Sonoran Desert

Abstract

A novel member of the yeast genus Pichia was recovered 67 times during the period 1971 to 1976. We have named this new species Pichia heedii in honor of William B. Heed. Most strains were isolated from the soft-rot of Lophocereus schottii and from Drosophila pachea, which utilizes L. schottii as a host plant. All strains were found in the Sonoran Desert. The species has four-spored asci and is heterothallic. P. heedii has metabolic capabilities similar to those of P. membranaefaciens, but the base composition of its nuclear deoxyribonucleic acid is 10 to 12 mol% lower than that of P. membranaefaciens. P. heedii may be differentiated from other cactus-specific Pichia species by its ability to assimilate D-xylose and from P. membranaefaciens by its cactus habitat, small cell size, and relatively high maximum temperature of growth. The type strain of P. heedii is UCD-FST 76-356 (= ATCC 34936 = CBS 6930).