Requirement for Ehb during conversion of the aryl acids to amino acids. The growth of wild-type strain S2 (A) and the ΔehbN mutant S965 (B) was evaluated. Media included complex McCA medium (•), McA medium containing aryl acids (⧫, 1 mM phenylacetate, indoleacetate, and p-hydroxyphenylacetate), and aromatic amino acids (▴, 1 mM tyrosine, phenylalanine, and tryptophan), both amino and aryl acids (▪), or no additions (○). For other experimental conditions, see the legend to Fig. 3.