Differentiation of pathogenic, gram-negative, bacterial genera in the presence of beta-2-thienylalanine.

Described in a fast screening assay for aid in the differentiation of bacterial genera. Salmonella is separated from Escherichia and Shigella, as a generic group on the basis of an inhibition assay incorporating beta-2-thienylalanine, and using a defined medium. The assay is also usable for confirmation of taxonomic differences between genera. The inhibition reaction, readable as an 'all-or-none' phenomenon, follows a dose-response relationship for cultures affected by beta-2-thienylalanine, and is unaffected by the growth phase of the culture.