Serratia marcescens: Masquerader of Blood

Some strains of S. marcescens are capable of producing pigment, the intensity of which ranges from dark red to pale pink, depending on the age of the colonies. The pigment can be present after incubation at room temperature but usually disappears after subculturing. The pigment was extractred by 1902 and named "prodigiosin" . Serratia marcescens has a predilection for growth on foodstuffs, especially of the starchy variety, where the pigmented colonies were easily mistaken for drops of blood. As early as the sixth century B.C., Pythagoras had noted the appearance of a bloody concentration on foodstuffs, and in the 1800’s, Ehrenberg uncovered almost 100 historical references to the miraculous appearance of blood on food.