I am doing in vitro characterization of two aroA mutants of E.coli using the minimal media (M9) with/without aromatic amino acids to compare the growth of wild-type strains and their mutant. The growth of one of the aroA mutant is restored in the M9 media supplemented with aromatic amino acids. But aroA mutant of the second strain did not grown in the presence or absence of aromatic amino acids. Same concentration of amino acids is used for both strains

4 mg of tryptophan, 4 mg of tyrosine, 4 mg of phenylalanine, 1mg of dihydroxybenzoic acid, and 1 mg of para-aminobenzoic acid per ml and was used as a 1-in-100 dilution in supplemented media. Can anyone explain the possible reason for the difference between two strains .