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Saccharomyces exiguus PDF Print
Sunday, August 01 2010 23:32

 

Genus/species (aliases): Saccharomyces exiguous (Candida holmii, anamorph, Cryptococcus holmii, Torula homii, Torulaspora exigua, Torulopsis alactosa, Torulopsis holmii)


Classification: Ascomycete, teleomorph 

 

Morphology:

Cell: reproduce by budding, spherical to ovoid or elongate, often arranged in pairs

Colony: Malt agar: white to cream-colored, shiny and smooth

Reproduction: 

  • Spore: smooth oval or spherical spores
  • Zygote:
  • Ascus: spherical, one to four ascospores, asci persistent

Liquid Growth: non-flocculent, no pellicle formation, no ring growth.

 

Physiological Traits:

  • Fermentation: Glucose, Galactose, Sucrose, Trehalose; variable: Raffinose
  • Assimilation: Galactose, Sucrose, Trehalose variable: Raffinose, Lactate, Succinate, Ethanol; No assimilation of nitrate or nitrite; no use of ethylamine, lysine or cadaverine as sole N source; No growth in vitamin-free medium, requires biotin and/or thiamin and/or pantothenate
  • Growth 37 C: negative
  • Growth Sensitivities: resistant to low (0.01%) cycloheximide; some strains resistant to 10% NaCl
  • Chromosome bands: 2 to 16 described

 

Ecological Traits: A wild yeast found on plants, fruits and grains.

 

Distinguishing Features:

Produces acid, uses NH4 2SO4 as primary source of Nitrogen.

 

Role in wine:

Has been reported in wine, but occurrence is rare.

 

Sensitivities:

  • SO2:
  • Sorbate­­­­­:
  • DMDC:
  • pH: Unknown
  • Acid high tolerance
  • Ethanol low tolerance
  • Anaerobiosis aerobic and semi-aerobic only
  • Heat 11C – 33C is tolerable range, 28C optimum

 

References:

Brocklehurst, T.F., White, C.A. & Dennis, C. The microflora of stored coleslaw and factors affecting the growth of spoilage yeasts in coleslaw. Journal of Applied Bacteriology, 55, 57-63.