I need a method for preparing LB agar plates with 1 mM concentration of AgNO3. I can not seem to find a method online, does anyone know of one that I could use?

Here are my main questions regarding the method:

a. Do I add the silver before or after I autoclave?

b. do I add the silver in a liquid form for powder?


  • $\begingroup$ Why do you want to add silver ions to a agar plate? Besides this: LB medium contains sodium chloride - which will react with the silver ions and form silver chloride which forms an unsoluble precipitate. Additionally silver chloride is light sensitive and will stain the plate black eventually. $\endgroup$ – Chris Dec 1 '16 at 13:23
  • $\begingroup$ Yes, that is true. However, bacteria which are silver sensitive still can not grow on the plate given these conditions. I am in need of growing silver resistant bacteria on an agar plate, and this is the method in which I want to do it. AgCl precipitate will occur, however some Ag ions will still remain in the agar. $\endgroup$ – A. Radek Martinez Dec 1 '16 at 14:13
  • $\begingroup$ If you consider the solubility product of AgCl (which is around 1,88mg/L at 25°C) and the fact that you add 10g/L NaCl, I doubt that there are notable amounts of Ag ions present in the medium. Aren't there any protocols available? $\endgroup$ – Chris Dec 1 '16 at 14:42
  • $\begingroup$ What you could try (and what I did a few times with antibiotics) is to dry the plates and then plate the solution on top of the plate. Then the ions are at least available at the surface layer. $\endgroup$ – Chris Dec 1 '16 at 14:44
  • $\begingroup$ I have done this before. Although the amounts of silver ions available may be minimal, silver sensitive bacteria can not grow on the plates. I have tried concentrations from 1mM - 10mM. The plates were prepared by a different person in my lab. However, I can not currently contact this person for instructions. $\endgroup$ – A. Radek Martinez Dec 1 '16 at 14:59

You add the silver after autoclaving. Just make sure that you make your stock concentration of silver in sterile water to avoid unwanted contamination. Do it in liquid form; it is easier to dilute from a stock.

  • $\begingroup$ Yes, this is what I found to be the standard when working with silver $\endgroup$ – A. Radek Martinez May 2 '18 at 14:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.