I am going to monitor dynamic fermentation using S.cerevisiae for bioethanol production in the future. The substrate/media I used is wheat flour mash. The growth curve of yeast is an important part in my thesis. I plan to measure the OD600 value at different time points.
This is the way I found in one paper, however I am not 100% sure about the details, and please correct them or give me some suggestions.
Samples (2mL) were drawn from each of the experimental and blank vials and OD600 was determined using the sample blank as the spectrophotometric zero reference. The sample blank refers to mash without any yeast inoculation. Due to the action of Stargen enzyme, each time point required the preparation of a new blank to compensate for the decreasing cloudiness of the starch solution.
My questions is: how to dilute the sample before I do OD measurement? Do I need to mix the sample with blank mash? if yes, do I need to filter the blank mash or not? I come up this question because in my fermentation system, the mash is a solid-liquid system which means it is very difficult to get them homogeneous.
Or if any of you have better options to measure OD value, please comment below. Thank you very much!!
You need to measure two blanks; First Blank should be the diluent solution you use to soak them. Second blank is mash without yeast inoculation. At each point or sampling time and measurements of OD, centrifuge at 120rev/min then measure the OD. Subtract results form 1st and 2nd blanks. Plot a standard curve with 1st blank and use it to assess the second Blank. If it gives a smooth curve, then use the mash without inoculation as blank and it's slope gradient for calculation. Thanks
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