Temporal production of p- HPA and p -cresol in mutant and wild-type strains using NMR. A) NMR spectra showing an overview of the relative levels of tyrosine, p-HPA and p-cresol from all replicates and strains tested over a 24-hour time period, the colours define the 44 samples used in the time course experiment, over four strains and media controls. T = time of sampling (hours post inoculation). B) The relative production of p-HPA by mutant and patent strains over a 24-hour time period. C) The relative production of p-cresol by the parent strains over a 24-hour time period. (The levels of p-cresol by the ΔhpdC mutants were below the limits of detection by NMR and were not plotted).