Cryptococcus laurentii

Genus/species (aliases): Cryptococcus laurentii; (Torulaspora laurentii; Torulopsis flavescens;Torulopsis flavescens;Cryptococcus flavescens; Rhodotorula laurentii; Torula flavescens; Torula laurentii);

Classification (ascomycete/basidiomycete): Basidiomycete

Morphology:

  • Cell: Ovoid, 2-5 x 3-7 µm in size, encapsulated, budding yeast, gathering in chains of 3-4.
  • Colony:
  • Malt agar: Smooth, glossy, cream colored colonies, darkening to yellow-orange; In C. laurentii var. laurentii mycelium may grow, mostly below agar surface
  • WL: Unknown
  • Spore:  In C. laurentii var. laurentii limited thick-walled ovoid – spherical  chlamydospores formed, with hyphal growth in those that germinate.  Less than 1% of spores germinate.
  • Zygote: Teleomorph not identified
  • Ascus: N/A (Basidiomcyete)
  • Liquid Growth: flocculent

 

Physiological Traits:

Capable of degrading a large variety of plant structural compounds including xylanases, pectinases, cutinases, lipases, proteinases and laccases. Can also degrade hemicellulose into anionic extracellular polysaccharides.

Ecological Traits:

Found in most soils, especially arctic, prairie and tundra. Avian fecal matter is often a reservoir for the genus. It is a more dominant fungus on unripe grape berries and continues to be present when grapes are ripe (particularly in cooler climates).

Distinguishing Features:

Facultative alkaliphile; psychrophillic. Produces yeast killing factor.

Role in wine:

Can occur as native fungi on grape skin and also found in cellars and in corks;  Rarely present in finished wine in significant quantities.  In corks, it may be responsible for some odor/contamination problems; Recent studies indicate may be useful as a biocontrol method in vineyard management, particularly as regards to Botrytis cinerea – especially as it can degrade laccase.

Sensitivities:  

  • SO2: unknown
  • Sorbate­­­­­: unknown
  • DMDC: unknown
  • pH: unknown
  • Acids: unknown
  • Ethanol: Low tolerance
  • Anaerobiosis: unknown
  • Heat : Max is 30 degrees Celcius

References:

König H., G. Unden and J. Fröhlich. 2009. Biology of Microorganisms on Grapes, in Must, and in Wine. Springer, New York.