Hi everyone!
I want to compare the cell growth and lysis of two strains of E. coliBL21 by optical density (OD) measurement at 600 nm. Considering the spectrophotometer read the microplate from bottom to top, it is possible detect the cell lysis phase ? and if so, why ?. Cell debris also scatter light.
Also I want to improve the protocol. The measurment should be done immediately after shaking, or shaking first then repose and immediately read?
Thanks!
A more quantitative method is to plate the cells on agar and count the number of viable colonies that grow overnight. Dead cells still scatter light, but they don't form colonies.
You can usually see lysis as a decline in OD600, for example by phage or chicken lysozyme. A completely lysed culture can go to near zero. That means, the debris scatter the light less, and usually a lot less, than whole E. coli.
You can rationalize this by size. E. coli is only a tad larger than 600 nm. So, the debris are usually going to be smaller than the wavelength of your light. That makes scatter very inefficient.
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