Lysis of yeast cells by Oenococcus oeni enzymes

Oenococcus oeni exhibited extracellular beta (1-->3) glucanase activity. This activity increased when cells were cultivated with glycosidic cell-wall macromolecules. In addition, the culture supernatant of the organism effectively lysed viable or dead cells of Saccharomyces cerevisiae. This lytic activity appeared in the early stationary phase of bacterial growth. Yeast cells at the end of the log phase of growth were the most sensitive. The optimum temperature for lysis of viable yeast cells was 40 degreesC, which is very different from the temperatures observed in enological conditions (15-20 degreesC). Moreover, the rate of the lytic activity was significantly lower in comparison with yeast cell wall-degrading activities previously measured in various other microorganisms. Therefore, yeast cell death that is sometimes observed during the alcoholic fermentation could hardly be attributed to the lytic activity of O. oeni.