1. Yeast
Microbe of the Day

2. Phylum Ascomycetes unicellular fungi
typically spherical, oval, cylindrical
typical size: 4.3 m x 4 m
cell division is by budding or fission
most are single cell; can be filamentous
facultative aerobes
wide habitat: grow where sugars are present
reference 1

3. Saccharomyces most well-known yeast Saccharomyces cerevisiase
commercially significant
Baker’s/brewer’s yeast
model eukaryotic system
complete genome sequenced (

4. Commercial Uses CO2 given off by yeasts expands (raises) dough
Yeasts ferment sugars to produce alcohol
top yeast = ales
bottom yeast = lagers
sulfur dioxide added to wine to prevent wild type organisms from fermenting
reference 2
reference 3
reference 4

5. Candida
yeasts can live on skin surfaces and in the intestinal tracts of warm-blooded animals
normal inhabitant
filamentous phase is necessary for pathogenicity

6. Opportunistic Pathogens
Candida albicans causes common “yeast infection”
Candidiasis of mucous membranes of mouth = “thrush”
Can also cause severe diaper rash
reference 5
reference 6

7. References