“…The average coefficient of variation for biological replicates (triplicates for the carbon-limited cultures with ammonium sul- a Three different network scenario hypotheses were employed to obtain an optimal fit for flux distribution: scenario i, phenylalanine was incorporated into protein, incorporated into penicillin G, metabolized via the homogentisate pathway, or metabolized via tyrosine; scenario ii, an unidentified pathway for phenylalanine metabolism, which did not involve any of the measured metabolites, was introduced into the model together with exchanges of phenylalanine and tyrosine with the protein pool (synthesis and degradation); and scenario iii, hypothetical hydroxylase activities that convert phenylpyruvate to 4-hydroxyphenylpyruvate and phenylacetaldehyde to 4-hydroxyphenylacetaldehyde were included. (14,26,27,36,68,71).…”