Studies on Flocculation Ofsaccaromyces Diastaticus, Especially Irreversible Deflocculation by Fe (Iii)*

Flocculation of Saccharomyces diastaticus was investigated. Although four strains tested formed flocs in the growing culture, they became dispersed in deionized water after washing with deionized water. Ca2+ was the most effective in promoting floc-formation not only in water but also in physiological saline. In contrast with reversible inhibition by Sr2+ and Ba2+, Fe3+ destroyed floc-forming ability irreversibly. Findings that treatment with proteolytic enzymes and chemical modification of cell surface protein and carbohydrate components-caused irreversible deflocculation and that D-mannose strongly inhibited flocculation suggest that cell surface protein and mannan components play essential roles in the flocculation of Saccharomyces diastaticus as well as in Saccharomyces cerevisiae. Fe3+ seems to bind firmly to the essential protein and cause significant deflocculation.