[Aromatic amino acid metabolism in Enterobacteriaceae microorganisms]

The authors revealed phenylalanine deaminase (PAD) in the majority of the Citrobacter strains investigated; the activity of PAD varied within a rather considerable range (0.3--4.58 micrometer of phenylpiruvate in 1 hr per 1 mg of bacterial protein). The presence of this enzyme thus served as an auxiliary biochemical test characterising this group of conditionally pathogenic microbes of the Enterobacteriacea family. Tyrosine decarboxylase was absent in 26 of 50 strains of Citrobacter examined. In the rest of the strains the activity of this enzyme was low. Consequently, tyrosine decarboxylase could not be used for identification of microorganisms of the Citrobacter genus.