I am working with yeast cells in shake flasks. When I transfer cells from primary medium to secondary medium, I usually calculate the required volume that needs to be transferred on the basis of OD I get in primary culture. Can we centrifuge cells and concentrate them and then transfer the cells to the secondary medium? Will centrifugation cause shear stress on the cells in this process? I am particularly interested in finding the growth rate.
Dear Nabamita Nandi
For secondary culture inoculation, you don't need to concentrate your cells by centrifugation. Measure the O.D., calculate the required volume, inoculate to the fresh secondary culture and study the growth.
Although yeast O.D. adjustment can be sometimes tricky as yeast cells scatter and absorb light. Due to the bigger size of the cells, it creates suspension and does not follow Lambert Beer law.
Best wishes.
Hi Nabamita Nandi
Yeast cells do create this problem of scattering and sedimentation, if left static. To be particular about your question, there is no need to concentrate cells from the primary culture. Instead, determine the OD600 for the primary culture, and transfer the volume of cells according to the OD600 value you desire in your secondary culture using the unitary method (or M1V1 = M2V2). This will serve the purpose of determining the growth rate of your desired culture.
Wish you Good luck!
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