The white bar indicates scale: 10 micrometres.

Photo credit: Allison Kwan, University of Western Ontario

Tortispora caseinolytica is notable for its apparent taxonomic diversity when its gene sequences from the large-subunit rRNA, the mitochondrial small-subunit rRNA, and cytochrome oxidase II are compared to those of other yeasts (Kurtzman et al, 2007). It occurs in the rotting tissues of opuntias cactus in the Sonoran desert. It does not ferment any sugars and it assimilates only a limited number of carbon compounds, including 2- and 5-ketogluconic acids. It exhibits strong extracellular proteolytic activity on casein at pH 6.5, but gelatin is not hydrolyzed or is only weakly hydrolyzed by a few strains (Phaff et al. 1994). When cultivated on a medium containing casein, it secretes an active, broad-range protease (Poza et al, 2001).