I am fermenting genetically engineered yeast with spent sulphite liquor to produce ethanol, however, after extracting samples and analysing the ethanol present, the concentration of ethanol decreases with time. I extract samples in a laminar flow cabinet so I am not sure if the extractor fan evaporates the ethanol or what I may be doing wrong.
At low concentrations, it is not easy to evaporate ethanol from an ethanol-water mixture. If your ethanol concentration is around 5-10%, I wouldn't suspect ethanol to be evaporating too much at 25-36°C.
If you still have some cells in contact with your samples after extraction, they might be using ethanol as a carbon source. I know when the substrate is depleted, Saccharomyces cerevisiae starts to consume ethanol. It may be the case with your yeast too. You can somehow sterilize your sample and keep it at 4°C to minimize the loss if that is the case.
Ibrahim Alper Basar Thank you very much for your answer. I suspected as much since my yeast strains are engineered from Saccharomyces cerevisiae.
Yes, it might, depending on the type of flow of the cabinet. Do you know which type of flow it is? Also, you just probably need o work fast and never leave the samples open.
I agree with Ibrahim's answer. When the carbon source is depleted, enzyme alcohol dehydrogenase might convert ethanol to acetaldehyde, which might cause the decrease in your ethanol concentration.
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