On the doublet formation in the flocculation process of the yeast cells

The combination of Single cells to form doublets is regarded as the rate-li miting step of flocculation and requires the presence of surface proteins i n active form. The process of activation of the flocculation proteins of ye ast cells is described in the frame of the autocrine interaction regime (Sc ience 224 (1984) 1312). The influence of several effecters (the cell effici ency to use sugars, the calcium content in the external medium and the prob ability that free cells collide each other under thermal motion conditions) on the initial rate of flocculation and on the fraction of remaining free cells in the steady state is briefly discussed in the paper. The present mo del offers a useful tool for further quantitative investigations in this to pic. Also, it indicates qualitatively a way in which the regulation of floc culation might be controlled at the level of the expression of cell-surface activation abilities. (C) 2000 Elsevier Science Ireland Ltd. All rights re served.