Brown- and red-pigmented Pseudomonas aeruginosa: differentiation between melanin and pyorubrin.

The pigment produced by three clinically isolated strains of Pseudomonas aeruginosa has been shown to by pyomelanin. The pigment is also produced by three strains of the same species labelled as "var. erythrogenes" by the National Collection of Type Cultures, and by Aeromonas salmonicida. Melanin and pyorubrin may be distinguished by the differential effects of tyrosine and glutamate on their production in minimal salts medium; Furunculosis Agar is a suitable medium for differentation of these pigments.