The fungus P. stipitis is a yeast from the xylose fermenting clade of the Schefferomyces genus. As with most members of the Saccharomycetales order a single P. stipitis individual has a size of 3 to 5 µm in diameter. Budding from asexual reproduction may cause deviation from the usual spherical or ellipsoidal shape of an individual. Under study it has been noted P. stipitis exhibits a cream-colored, smooth-shaped colony [5]. A suitable habitat for P. stipitis includes damp or wet areas rich in organic biomass [8]. Hardwood forests or areas high in agricultural waste are common environments. Temperatures at which growth occurs are 25°C to 37°C with budding most commonly occurring at 25°C. Studies have shown growth ceases at temperatures around 40°C to 45°C [5].
The significance of P. stipitis to industrial-related purposes comes from the ability to ferment the sugar, xylose [4]. Degrading biomass to ethanol at high yields in respect to other ethanol-producing microorganisms has made P. stipitis an important constituent of the alternative fuel and bioenergy industries [7].