Prodiginines are red-pigmented natural antibiotics that are produced as secondary metabolites and have received renewed attention because of potential clinical interests. In Serratia sp. or actinomycetes such as Streptomyces coelicolor, the tripyrrole molecules of prodigiosin and undecylprodigiosin are formed by the condensation of 4-methoxy-2,2'-bipyrrole-5-carbaldehyde and either 2-methyl-3-n-amyl-pyrrole [MD:M00837
] or 2-undecylpyrrole [MD:M00838
]. The Serratia pig gene cluster and the Streptomyces red gene cluster responsible for these biosynthesis pathways have been identified.