STUDIES ON FLOCCULATION: I. A RELATIONSHIP BETWEEN THE pH AND CALCIUM CONTENT OF THE GROWTH MEDIUM

Several strains of flocculent top fermentation yeasts have been grown up and allowed to sediment in various semi-synthetic media with calcium contents of 2–200 p.p.m. in a pH range of 3·1–4·6. It has been shown that, at the lowest pH levels, the cells were unable to flocculate, but as the pH was raised so they became increasingly able to flocculate. The extent of the well-known stimulation of flocculation by calcium has been shown to be dependent on the pH of the growth medium and to vary tremendously from strain to strain. On the basis of this response to calcium and pH, the strains examined can be regarded as falling into three well-defined types.