Question

You have 5ml of an overnight culture (2x10⁸ cells per ml). How would you prepare a series of 1 or 10ml dilutions (maximum dilution 1:100) to obtain a final 200 ml culture at 1x10³ cell/ml? Provide work for each step.

Answer 1

Start by adding 1ml of the stock in 10ml of media and serially dilute this for subsequent 3 times at a dilution of 1:10. When you obtain a concentration of 2*10^4 cells, take the 10ml of diluted culture and add into 200ml of media which will give a final dilution of 1*10^3 cells/ml. The detailed calculation is as given below: