Application of yeast spores as β-glucan particles

β-Glucan exhibits various beneficial biological activities including immunostimulation.This polysaccha-ride is present in the cell wall of microorganisms including the yeast Saccharomyces cerevisiae.Although vegetative yeast cells are used as dietary supplements,β-glucan in the vegetative cell wall is covered with mannan.During nutrient starvation,yeast cells differentiate into dormant cell spores.β-Glucan is also present in the spore wall,but spores have been poorly studied as application tools.The spore wall consists of four layers andβ-glucan forms the third layer from the outside.However,unlike vegeta-tive cells,theβ-glucan layer can be exposed to the cell surface in spores by genetic manipulation.For example,chs3Δmutant spores exhibit such a spore wall configuration.Dectin-1 is the primary receptor forβ-glucan in mammals and,its activation induces phagocytosis and proinflammatory cytokine secre-tions.We found that chs3Δspores are phagocytosed in mammalian cells in a manner dependent on dectin-1 and induce higher levels of TNF-αand IL-6 than vegetative cells.Our results demonstrate that chs3Δspores areβ-glucan particles with immunostimulatory activities.Thus,they would be attractive materials for application in the food industry.