Taxonomy and ecology of the genus Candida

Candida is a heterogeneous genus which contains about a quarter of all yeas t species. It includes not only species of uncertain affiliation but also u nrelated strains whose phylogenetic relationships have not been resolved. A great variety of CoQ types are present in the genus, the mol % G+C ranges from 30-63%, and species that were found to sporulate have teleomorphic cou nterparts in 11 different genera. Candida species are mainly associated with plants, rotting vegetation, with insects which feed on plants or with food. In line with this, 71 % of Cand ida species utilize xylose (wood degradation), 57 % of species use cellobio se (cellulose degradation), 29 % oxidize aliphatic hydrocarbons (components of plant cuticula), 27 % of species degrade starch as a plant storage mate rial, and 7 % utilize methanol as a possible metabolite from pectin catabol ism. 85 % of species require individual vitamins produced mainly in plant m aterials. 65 % of Candida species are not able to grow at temperatures of 3 7 degrees C. In comparison only relatively few species occur normally in humans and othe r warm blooded animals. About 16 % of type strains and selected strains for comparative purposes (CBS) were isolated from human specimens. Perhaps up to 10 % of Candida species may be of medical importance, though this has so far only been clearly demonstrated for less than 5 % of currently known sp ecies.