Pichia deserticola and Candida deserticola, Two New Species of Yeasts Associated with Necrotic Stems of Cacti

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Abstract
P. deserticola sp. nov. and C. deserticola sp. nov., 2 species that have as their habitats necrotic tissues of Opuntia spp. and Stenocereus spp., respectively. P. deserticola, 21 strains of which were isolated, is homothallic and occurs in nature exclusively in the diploid state. It produces asci with 2 hat-shaped spores, which are rapidly released upon maturity. This species is nonfermentative and assimilates few C compounds. The guanine-plus-cytosine content range of the nuclear DNA (8 strains) is 27.4-28.4 mol% and the average .+-. SD for 8 strains is 27.8 .+-. 0.4 mol%. C. deserticola, 48 strains of which were isolated, has the same phenotypic properties and DNA base composition as P. deserticola, but lacks the ability to produce ascospores and is resistant to triterpene glycosides in growth media. DNA of P. deserticola and C. deserticola show > 96% homology, but the 2 species are separated geographically and by host plant. P. deserticola occurs in Opuntia spp. in southern Arizona and Texas, USA, whereas C. deserticola is found almost exclusively in columnar cacti of the genus Stenocereus on certain Caribbean islands and in Baja California, Mexico. The type strain of P. deserticola is strain UCD-FST 83-467.3 (= ATCC 58091 = CBS 7119), and the type strain of C. deserticola is strain UCD-FST 76-355A (= ATCC 58088 = CBS 7121).