The Genus Serratia

Abstract

The genus Serratia a member of the Enterobacteriaceae (see Introduction to the Family Enterobacteriaceae from the second edition.), is comprised of a group of bacteria that are related both phenotypically and by DNA sequence. The type species of the genus is Serratia marcescens. Some species and biotypes of Serratia produce a nondiffusible red pigment, prodigiosin, or 2-methyl-3-amyl-6-methoxyprodigiosene (Williams and Qadri, 1980). The multiplication of red-pigmented Serratia was incriminated in the appearance of bloodlike spots (e.g., on bread, consecrated wafers [sacramental Hosts], and polenta) with rather disastrous sociological consequences. In this context, several scholars have traced the history of the genus Serratia back to antiquity (Gaughran, 1969; Harrison, 1924; Reid, 1936). However, several bacterial species outside the genus Serratia produce prodigiosin or prodigiosin-like pigments (Williams and Qadri, 1980) or many other kinds of red pigments, and the identity of microorganisms involved in these striking phenomena can only be surmised.