English: Pseudomonas aeruginosa growing on sheep blood agar at 37 °C after 24 h (A, C, E, F) and 48 h (B, D, G, H, I, J). P. aeruginosa strains are frequently haemolytic (B, D, G, J; reflected + transmitted light). This species gives rise to a variety of colony types. Most of the colonies are smooth, but varying grades of roughness may occur. Figure I shows an image of colonies with a “beaten-copper“ surface and slightly irregular edge. Capsulated strains of P. aeruginosa, usually isolated from patients with pneumonia, produce large, mucoid colonies (Fig. H). On routine blood agar, the typical P. aeruginosa colony is pigmented (gray/gray-white with a yellowish tint through green to red or brown). Pigment production is usually better visible and more profound on transparent media (e.g., Mueller-Hinton agar).