I need it for the Kd measurement after 10 rounds of SELEX. Yes you are right for SELEX in first round in some research they started with higher range of CFU/ml later they reduced...

It depends on your bacteria, but based on different studies the minimum number of bacteria should be 1000 cfu/ml.

for more information please check these two papers.

1- https://doi.org/10.1371/journal.pone.0185385

2- Utilizing Cell-SELEX, as a Promising Strategy to Isolate ssDNA Aptamer Probes for Detection of Staphylococcus aureus

Good luck

Negar Bagheri Thank you. I am really obliged with your comprehensive reply.

Aysha Shaukat your welcome, Good luck Aysha