Question

You are doing an experiment involving antibiotic resistance in your study bacteria. This organism grows well on LB - Miller agar plates. You want to make 50 plates (assuming 25ml/plate) of LB-Miller at 1.5% agar concentration. Twenty-five of these plates will be plain, the other 25 need to contain 50 micrograms/ml of Gentamycin for your resistance experiments. You have a stock solution of Gentamycin at a concentration of 5 mg/ml. How would you go about making your plates

Answer 1

Answer:

See the answer below

Explanation:

The stock solution of Gentamycin has a concentration of 5 mg/ml while each plate needs to contain 50 micrograms/ml of Gentamycin.

5 mg/ml = 5000 micrograms/ml

There is a need to dilute the stock antibiotic solution in order to arrive at 50 micrograms/ml. Using the dilution principle;

m1v1 = m2v2

5000 x 1 = 50 x v2

v2 = 5000/50 = 1000 ml

Hence, in order to prepare 50 micrograms/ml, 1 ml of the stock Gentamycin should be taken and diluted with 999 ml of distilled sterilized water. 1 ml of the diluted Gentamycin will then be added to each agar plate while they are still in the molten form at a warm temperature.