"Mint" or "Lime" Green Indicator Plates



Mint Green plates, sometimes called "Lime Green", replace the more toxic Standard Green plates. They are used to detect Salmonella free of P22 contamination, and, in H5 cross-streak tests, allow detection of strains lysogenic for P22. See Jeff Lawrence's discussion on how green plates work.

Plate Preparation

Flask A (1 liter vol)
         10 g    Tryptone       
         5 g     Yeast Extract  
         5 g     NaCl   
         2.5 g   Glucose        
         15 g    Agar   
         H2O to 500 mL
         Stir bar
Flask B (1 liter vol)
         0.5 g   K2HPO4⋅3H20  
         H20 to 500 mL
Autoclave both flasks at 121°C. Allow medium to cool to ~60°C, add flask B to flask A with stirring, and add to the cooling medium the following dyes:
        1.25 mL Evans Blue stock solution
        2.5 mL  Uranine stock solution
Pour plates in the usual fashion and store in cold room. They are relatively stable over time.

        Evans Blue: 1% w/vol in H20 -- autoclave, store in dark
        Uranine:    1% w/vol in H20 -- autoclave, store in dark

Maloy, S., V. Stewart, and R. Taylor, Genetic Analysis of Pathogenic Bacteria: A Laboratory Manual. 1996: Cold Spring Harbor Laboratory Press.