Rhodotorula

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Rhodotorula
Rhodotorula mucilaginosa 400x img430.jpg
Rhodotorula mucilaginosa cells, Methylene blue stain, magnification 400 x
Scientific classification
Kingdom: Fungi
Phylum: Basidiomycota
Class: Urediniomycetes
Order: Sporidiales
Family: incertæ sedis
Genus: Rhodotorula
Harrison, 1927
Species

See text.

Rhodotorula mucilaginosa colonies on Sabouraud agar (with 2 % glucose).

Rhodotorula is a unicellular pigmented yeast, part of the Basidiomycota phylum, quite easily identifiable by distinctive orange/red colonies when grown on SDA (Sabouraud's Dextrose Agar). This distinctive color is the result of pigments that the yeast creates to block out certain wavelengths of light that would otherwise be damaging to the cell. Colony color can vary from being cream-color to orange/red/pink or yellow. Microscopic morphology shows spherical to elongated budding yeast-like cells or blastoconidia. Rhodotorula ranges in size from 2.5-6.5*6.5-14.0 um. When an India Ink Preparation is done Rhodotorula presents with a small capsule present. Germ Tube test gives a negative result. Hydrolysis of Urea test gives a positive result. Rhodotorula does not grow on Cycloheximide medium. The Dulmau Plate culture on Cornmeal and Tween 80 agar shows budding blastoconidia only, no pseudohyphae are formed. [1]

Rhodotorula is a common environmental inhabitant. It can be cultured from soil, water, milk, fruit juice, and air samples. [2] It is able to scavenge nitrogenous compounds from its environment remarkably well, growing even in air that has been carefully cleaned of any fixed nitrogen contaminants. In such conditions, the nitrogen content of the dry weight of Rhodotorula can drop as low as 1%, compared to around 14% for most bacteria growing in normal conditions. [3]

The genus Rhodotorula includes eight species, of which only R. mucilaginosa, R. glutinis, and R. minuta have been known to cause disease in humans. There were no reported cases of Rhodotorula before 1985. [4] There were however forty-three reported cases of Rhodotorula bloodstream infections (BSIs) between 1960 and 2000. [5] Rhodotorula is most commonly found in patients who are immunosuppressed and/or are using foreign-body technology such as central venous catheters. [6] Rhodotorula is commonly treated by removing the catheter and the use of antibiotics. Rhodotorula is susceptible to Amphotericin B and Flucyosine. [7]

Rhodotorula can also cause infections in animals. There have been reports of skin infections in chickens and sea animals and lung infections and otitis in sheep and cattle. [8]


Species[edit]

External links[edit]

Notes[edit]

  1. ^ The University of Adelaide, “Rhodotorula rubra”, Mycology Online, 2014
  2. ^ Fernanda Wirth and Luciano Z. Goldani ”Epidemiology of Rhodotorula: An Emerging Pathogen” Interdisciplinary Perspectives on Infectious Diseases, 2014
  3. ^ Postgate, John: "The Outer Reaches of Life", page 132-134. Cambridge University Press, 1994
  4. ^ Fernanda Wirth and Luciano Z. Goldani ”Epidemiology of Rhodotorula: An Emerging Pathogen” Interdisciplinary Perspectives on Infectious Diseases, 2014
  5. ^ Aimee K. Zaas, “Risk of Fungemia Due to Rhodotorula and Antifungal Susceptibility Testing of Rhodotorula Isolates” Journal of Clinical Microbiology, 2014
  6. ^ Aimee K. Zaas, “Risk of Fungemia Due to Rhodotorula and Antifungal Susceptibility Testing of Rhodotorula Isolates” Journal of Clinical Microbiology, 2014
  7. ^ Aimee K. Zaas, “Risk of Fungemia Due to Rhodotorula and Antifungal Susceptibility Testing of Rhodotorula Isolates” Journal of Clinical Microbiology, 2014
  8. ^ Fernanda Wirth and Luciano Z. Goldani ”Epidemiology of Rhodotorula: An Emerging Pathogen” Interdisciplinary Perspectives on Infectious Diseases, 2014