I cultured Saccharomyces cerevisiae in YPD broth and incubated different flasks (some of them treated with a vegetable peel)in a shaker water bath for 48 hours at 30c. the untreated yeast cultures were ended up with a white layer of yeast growth at the top of the flask. it was tough enough that I couldn't homogenize the samples. I want to measure yeast growth indifferently treated flasks. Is there any way for preventing such a layer? or measuring the yeast growth correctly?
Hi there,
Light sonication on homogenized cell culture sample prior cell counting seems to be the easiest way to proceed.
Worked in the past with different S. Cerevisiae strains ( some were high flocculation) and never saw what you are describing. I think J. Stolz is right suggesting a contamination (some bacteria would make a though film a the top of a liquid culture e.g. acetobacter or kombucha SCOBY). Some strains of S. Cerevisiae could definitely clump in the top foam but not the point of having something difficult to re-suspend. Eventually if your shaker stopped functioning for a long time during the cell growth that could happen. I would also advice to have a look under microscope.
well, I have worked with some glycosylation mutants, that were extremely sticky. The mnn9 mutation for example is lethal in some strain backgrounds, but when the cells are alive you deal with overnight cultures that are sometimes crystal clear and have only 1 or two big balls of cells at the bottom of the flask. the timeframe you describe (48 h at 30 C) in YPD based media is also not typical for what you would expect from yeast.
Dear all, thanks for all of your answers. I am going to repeat the experiment, focusing on the information you have shared with me.
thanks once again.
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