Rhodotorula mucilaginosa

Genus/species (aliases): Rhodotorula mucilaginosa (R. rubra, R. pilimanae, Sporobolomyces albo-rubescens, Saccharomyces ruber, and numerous other synonyms)

Classification: Basidiomycete, anamorph

Morphology:

Cell:  reproduces by budding; Spherical to elongate, simple pseudohyphae may be formed by some cells

Colony;

  • -5% malt extract agar: (after 3 days) ovoid to spherical, 2-8 x 2-12 um, reproduction by multilateral budding, singly, pairs, short chains, small clusters, pink color rings
  • -Malt extract agar: (after 1 month) orange to pink to coral colored colonies. Cross section is flat, surface varies from smooth to rugoid and dull to glistening. Margin is entire
  • -Cornmeal agar: (after 1 month) pseudomycelium is absent or rudimentary, chains of elgate cells
  • -Subouraud dextrose agar: orange-pink, smooth-rugoid, dull-glistening, usually pigmented (pinkish) color

Reproduction:

  • Multilateral budding, no sexual cycles, no blallistoconidia
  • Spore: NA
  • Zygote: NA
  • Ascus: NA

Liquid Growth: moderate pink ring may form

 

Physiological Traits:

  • Fermentation: Absent
  • Assimilation: Glucose, Ribose, D-Xylose, Arabinose, Sucrose, Trehalose, Raffinose, Xylitol, Succintate; variable use of: Galactose, Sorbose, Arabinose, Rhamnose, Maltose, Cellobiose, Salicin, Arbutin, Mlezitiose, Citrate, Lactate, Gluconate, Galactitol, Mannitol, Glucitol, Arabinitol, Glycerol, Ethanol; variable assimilation of nitrate and nitrite; uses tryptophan as sole N source; variable use of ethylamine, lysine and cadaverine as sole N source; No growth in vitamin-free medium, requires thiamin
  • Growth 35, 37 C: variable
  • Growth Sensitivities: variable for growth on cycloheximide, high NaCl and high glucose
  • Chromosome bands: 10 reported
  • Obligate aerobic yeast that contains a high concentration of carotenoid pigment
  • Urease positive

Ecological Traits:

Rhodotorula spp. are widespread, from soil, water, air. Exceptionally well at scavenging for nitrogen. In wineries, may be present via water contaminant. In vineyards, may be found in grape skins.

Distinguishing Features:

  • Rhodotorula spp are unique from other yeasts by positive growth on Sabouraud’s Dextrose Agar (SDA) media, resulting in  distinctive pigmented colonies.
  • Negative nitrate assimilation helpful for identification of positive nitrate Rhodotorula spp.
  • Closely related to several Rhodotorula spp., therefore genetic tests may be necessary for positive identification.
  • May represent anamorphic stages of Rhodosporidium, Leucosporidium, and other genera with simple septal pores.

Role in wine:

Is considered a non-desirable (non-Saccharomyces) yeast by many winemakers. But, it is not necessarily considered a spoilage yeast. Found in many wine regions both in vineyard and winery environments.

Sensitivities:

Sensitive to ethanol, antifungals, anerobiosis, temp above 40oC, extreme pH, some mycocins from Sporidiobolus para, andRhodotorula glutinis

SO2: Unknown

Sorbate­­­­­:Unknown

DMDC: Unknown

pH: Yes

Acids:Unkown

Ethanol: Yes

Anaerobiosis: Yes

Heat: Yes  

References:

Quesada M., J. Cenis. 1995. Use of Random Amplified Polymorphic DNA in the characterization of wine yeasts. AJEV. 46,2,204-208.

Tags

Yeast & Mold