Cryptococcus bhutanensis

Abstract: Publisher Summary This chapter focuses on Cryptococcus genus and its member species. The cells of this genus are spheroidal, ovoidal, or elongate, and reproduction occurs by multilateral or polar budding. Ascospores, ballistospores and ballistoconidia are not formed, and colony color on solid media may be white or cream and some strains produce red, yellow or brown pigments. All species utilize D-glucuronate and most species synthesize starch. Those species that do not synthesize starch utilize inositol, a combination that distinguishes those species from Rhodotorula spp. The member species of this genus include Cryptococcus aerius, Cryptococcus albidosimilis, Cryptococcus albidus, Cryptococcus amylolentus, Cryptococcus antarcticus, Cryptococcus aquaticus, Cryptococcus ater, and Cryptococcus bhutanensis. The cells of Cryptococcus aerius, after undergoing growth in malt extract for 3 days at 20° C, appear as globose to ovoidal, and maybe single, in pairs and often in small clusters or in short chains. The cells of Cryptococcus albidosimilis, after undergoing growth in 1% glucose-yeast extract-peptone water, appear as ovoid, encapsulated and functionally monopolar. The organisms slowly produce a scantyannulus and a little sediment.

Abstract: SUMMARY Cryptococcus bhutanensis, C. himalayensis and C. vishniacii are anamorphic basidiomycotinous yeasts. Cryptococcus bhutanensis and C. vishniacii are the first such reported to lack extracellular urease. The budding characters of these three species occur in an association here described for the first time in yeasts. Budding is monopolar and repetitive through the site of the birth scar. The primary bud is holoblastic, secondary buds enteroblastic and continuous with the inner wall layer of the entire parental cell. Septum formation occurs at or slightly above the level of any previously formed collar (bud scar). The Cryptococcus species, budding monopolarly, have a higher width:length ratio (0.70 to 0.83) than the bipolarly budding Leucosporidium scottii (0.55), in which primary buds are distal to the birth scar. Surface topography reflects the degree of cell encapsulation, but appears to result in part from artifacts of capsule collapse during drying in thinly encapsulated cells. Size, shape, surface topography and the details of budding observable with scanning and transmission electron microscopy are major descriptors of yeast cells, particularly valuable for yeasts which fail to reproduce sexually. A list of the budding characteristics which have been useful at various hierarchical levels in systematic schemes as well as in ontological studies (see 13, 21) should include the relative age of primiparous cells, the sites of primary and successive buds, the relation of budding sites to cell shape, the origin of the bud cell wall, septum formation and partitioning, and the resultant appearance of bud and birth scars. Despite this, size is frequently not described in statistical terms, shape is rarely described quantitatively, and there are few yeasts other than Saccharomyces cerevisiae Hansen for which available evidence yields an inclusive picture of the budding process. We here report morphological investigations of an ecologically interesting group of yeasts, psychrophiles or psychrotrophs isolated