Do you please know me how to add Solid Chloramphenicol, azithromycin, ciprofloxacin, amoxicilin and other water insoluble antimicrobials to nutrient agar, and potato dextros agar for endophytic fungus culture. Some have told to prepare stock solution with ethanol. But ethanol is a disinfectant itself. Will it have any effect on fungi?Then how can i dissolve the antimicrobials to the culture medium. Humble request to the experts helping me to solve the problem as early possible.
By solid assuming you mean powdered form. We use amoxicilin and kanamycin in LB agar. I mix the antibiotic in DI water to get the correct concentration before we pour into the media. I make the media, autoclave then wait for the agar to cool to 55 degree's C to add the antibiotic mixed in DI water......any hotter then 55 and you could deactivate the antibiotic so you have to be careful and make sure to run some kind of control. Once the antibiotic is added a gentle swirl to mix and pour into plates. Works great for us with no issues.
If you have to dissolve your antibiotic in ethanol, just do a try with ethanol alone as a control. All is a question of final concentration of ethanol.
As an example, with chloramphenicol I dissolve in 50% ethanol. I make the concentration of the stock solution 100-fold greater than the final concentration in the medium. This means that the medium has a maximum of 0.5% ethanol, and that doesn't account for the amount of ethanol lost by evaporation (which I think would be significant, e.g. plates poured at about 50°C, and then dried in an oven after they have set). I imagine the final concentration of ethanol in the plate when it is used is insignificant, and am sure that it will not cause growth inhibition.
Very very thanks to you for your valuable answer and time and good wishes for you.
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