Saccharomyces, from the Latin, literally means "sugar fungus," and is the scientific name for the yeasts used in fermentation, specifically baker’s yeast. Cosmetic ingredient manufacturers extol this yeast as having significant properties for skin, but there is little independent research supporting its use. However, some extracts of yeast, such as beta-glucan (a potent antioxidant) are derived from yeast.
References for this information:
Proceedings of the National Academy of Sciences, August 15, 1989, pages 6018–6022