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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?

Thanks.

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  • $\begingroup$ 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, 2016 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, 2016 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, 2016 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, 2016 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, 2016 at 14:59

1 Answer 1

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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.

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  • $\begingroup$ Yes, this is what I found to be the standard when working with silver $\endgroup$
    – A. Radek Martinez
    May 2, 2018 at 14:06

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