Effects of glucose and mannose on the flocculation behavior of Saccharomyces cerevisiae at different life stages

The temporal flocculation behavior of Saccharomyces cerevisiae at different life stages is investigated using glucose and mannose as the different carbon sources, and the temporal variations of cell size, zeta potential and stability ratio of cell suspension are measured. It is found that the largest cell size and the lowest stability ratio of cell suspension occurred at the middle period of the exponential growth phase independent of carbon sources. The colloidal aspect was analyzed by using the DLVO theory, and indicated that the gravitational force plays a major role in determining the flocculation behavior of yeast cells.