I want to calculate total number of Rosetta cells by using OD 600 , please explain.
You can estimate that an OD600 of 1 corresponds to approximately 8 x 108E. coli cells per ml.
Thanku very much Adam , if OD is 2 so how to calculate it ? As I already know the value of OD 1 but if it is more than 1 then how to calculate it? Please explain
Mathematically, an OD of 2 would correspond to 2 x (8 x 108) cells/ml = 1.6 x 109 cells/ml. That is assuming that the OD is directly proportional to the number of cells over that range of OD. However, that may not be accurate (an OD measurement of cells is not the same as an absorbance measurement, so Beer's Law does not apply), so you should dilute the cell suspension 2-fold or more to get it into the range of OD 1 or less.
So let's suppose, as an example, that you measured the OD of your undiluted cell suspension and it was 2. Then you decided to dilute the cell suspension 4-fold (250 µl of cell suspension + 750 µl of medium), and remeasured the OD and it was 0.7. From that you would calculate the approximate number of cells/ml to be 4 x 0.7 x 8 x 108 = 2.24 x 109 cells/ml.
By using OD600 I wanna calculate total RNA of bacterial cell. For OD600 of 1 there are 8*10^8 cells /ml. 1 cell has 0.10pg of RNA so 8*10^8 cells will have 80mg of RNA for 1ml culture so for 5ml culture total RNA will be 400mg. Am I right please suggest?
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