Study On Correlation Between Zeta Potential With Flocculation And Senility Of Saccharomyces Cerevisiae

Saccharomyces cerevisiae as a simple eukaryotic unicellular organism, is the most thorough microorganism studied by human beings and is also the typical model organism in the scientific studies. It is widely used in brewing, pharmaceutical and food industry. Yeast flocculation and aging has been the hot topic of researchers, and the stand or fall of flocculation is directly related to the separation of products from the fermented broth, the aging tends to cause the flocculation of yeast cells directly. Prematurely flocculation of yeast cells will make fermentation end ahead of time which affects the quality and yield of products. Zeta potential as the indicator of the property of particles has not been used in the study of microorganisms in the domestic, and also rare overseas. Given this, in this paper Saccharomyces cerevisiaes were used to explore the relationship between flocculation and aging with zeta potential of yeast.In this paper, the content of experiments are as follows:(1) Different Saccharomyces cerevisiae, prokaryotic and klebsiella bacillus were cultivated to get plenty of thallus.(2) Zeta potential of Saccharomyces cerevisiae was measured to explore how it changes with the variety of ion strength.(3) Zeta potential and yeasts flocculation experiments were carried out to explore interactions between zeta potential and Saccharomyces cerevisiae of which how it works in the process of yeasts flocculation.(4) After continuous cultivating, yeasts growth curve and the consumption rate of glucose was measured and gained different aging yeast thallus.(5) Different aging Saccharomyces cerevisiae cell walls was observed using scanning microscopy.(6) Changing yeasts culture conditions, such as temperature, dissolved oxygen, variation on zeta potential was analyzed under different cultivate conditions.Experiments results showed that Saccharomyces cerevisiae have negative zeta potential, and they don't change so much in the cultivation process, and zeta potential decreases with the strengthened ion strength. Comparing of yeasts with E. coli and klebsiella bacillus on zeta potential to explore the differences between different yeasts and eukaryotic with prokaryotic microorganisms which shows big diversity. In order to further explore the physical mechanism of flocculation and the interactions between yeast zeta potential with flocculation, zeta potential was converted to analysis the flocculation and its structure which shows good flocculation effectiveness as zeta potential is reduced. Analysis of different aging, temperature and aerobic or anaerobic conditions on zeta potential shows that there is no big difference of different aging yeasts, however it shows great difference between different temperatures and aerobic with anaerobic cultivate condition. It follows that zeta potential of Saccharomyces Cerevisiae is influenced by many factors, great difference does exist between yeast species. Decreasing on zeta potential of Saccharomyces Cerevisiae can cause yeast flocculation which is not the main reason that would cause its flocculation. There is no big difference between different aging yeasts, temperature and dissolved oxygen condition however have a big influence on zeta potential.