PHYLOGENY OF PHOSPHOMANNAN-PRODUCING YEASTS I. The Genera

Abstract

Primitive yeasts of the genera Hansenula, Pichia, and Pachysolen produce extracellular phosphorylated mannans. The.phosphomannans cause adherence of the cells to bark beetles that transport the yeasts from the sap-conducting tissues of one tree to another. Two yeasts that produce phosphomannans most abundantly are the most primitive species of Hansenula H. holstii is heterothallic, and H. capsulata is homothallic. From these two species issued lines of species developing toward independence from trees as their habitat and other lines that developed toward greater dependence upon trees. Most of the primitive species of Pichia are very similar to those species of Hansenula that are highly dependent upon trees. The one available species of Pachysolen resembles species of the less dependent lines.