Action of deflocculating agents on Saccharomyces cerevisiae Class III brewer's yeast.

Earlier work with a fluorescent aid indicated that flocculent brewer's yeast may have more surface lipids than nonflocculent types. Organic solvents were checked against flocculent Gilliland yeasts. It was found that those reagents which affect "free" lipids had no dispersive action, and those which remove "bound" fats had a powerful dispersive action against such yeasts. There was no indication that such an action could be correlated with other physical properties of the solvents. The uranyl ion is known for its ability to complex with phospholipids, and it was found to have a powerful dispersive action on Gilliland yeasts. Its effect was compared with that of glucose in its dispersion of yeast flocs, and possible cell "sites" were suggested. This, along with other work, suggests the possibility that lipids are directly or indirectly involved in yeast flocculation.