Detection of carboxypeptidases as taxonomic markers for gram-negative bacteria.

The use of seven benzoyl-L-amino acids for the detection of carboxypeptidase activities in strains of Gram-negative aerobic and facultatively anaerobic bacteria is reported. A simple overnight assay was designed using ninhydrin for the demonstration of the amino acid released by hydrolysis. Detection of carboxypeptidase activity was shown to have some taxonomic relevance within the Enterobacteriaceae; it was also useful for differentiation within the genus Acinetobacter and for distinction between Pseudomonas aeruginosa and Pseudomonas fluorescens.