| Yeasts (general) | - generally unicellular
- aerobic or facultative anaerobes
- can grow over wide range of pH, alc, sugar, and water concentrations
- color ranges from cream-pink-red
- some produce asco/arthrospores |
| Saccharomyces | - ascospores; multilateral budding
- yeast
- round, oval, or elongated cells
- Saccharomyces cerevisiae: used in baking, beer/wine production
- Saccharomyces bailii: spoil tomato sauce, mayo, salad dressing, juice, cider, wine |
| Schizosaccharomyces | - osmophilic yeast
- likes acidic conditions, can grow in high sugar
- ascospores
- resistant to some chemical preservatives |
| Zygosaccharomyces | - osmophilic yeast
- ascospores
- multilateral budding
- Zygosaccharomyces rouxii can grow at aw = 0.62
- used in shoyu and miso fermentation |
| Pichia | - thrives in low aw
- yeast, ascospores shaped like derby hats
- multilateral budding
- spoils alcoholic liquors, sauerkraut, pickles |
| Debaromayces | - ascospores
- yeast that has multilateral budding
- highest [NaCl] growth (24% at aw=0.65)
- common in dairy products |
| Candida | - yeast with ascospores and pseudomycelium
- pellicle on surface of liquids
- no carotenoid pigments
- spoilage of ground beef, poultry, cured meats
- Candida lipolytica: spoils dairy products, produces lypases to break down fats |
| Rhodotorula | - yeast with multilateral budding
- pink to red pigments
- many are psychrotrophic (grow in fridge)
- non fermenters
- found on fresh beefs, poultry, fish; red spots on sauerkraut |
| Torulopsis | - pseudomycelium yeast
- multilateral budding
- Torulopsis versatilis: ferments lactose, can spoil milk/fruit concentrates/acidic foods |
| Kloeckera | - pear shaped yeast with bipolar budding
- fermentative and oxidative
- spoils wine, fruit, and fruit juices
- Kloeckera apiculata |
| Trichosporon | - yeast, true mycelium formed
- produce lipase
- psychrotrophic
- sugar fermentation weak or absent
- found on refrigerated meats |
