8Kb; hpdC 3.4 kb and for R20291: hpdA – 6.3 kb; hpdC – 3.4 kb. Analysis of the decarboxylase mutants Initial growth dynamics and NMR spectroscopy analysis revealed that the hpdB, hpdC and hpdA mutants were indistinguishable in terms of the complete lack of p-cresol production in rich media supplemented with p-HPA (Figure 4A). Subsequent analysis ZD1839 price was performed with the hpdC mutants as these were constructed in both parent strains R20291 and 630Δerm. Growth curves in minimal

media (YP broth) revealed that the R20291ΔhpdC mutant grew significantly better than the parent strain R20291, however, no significant difference in in-vitro growth was observed between 630ΔermΔhpdC and the respective parent strain (Figure 4B). There were no significant selleck inhibitor differences between the tolerance of the mutants R20291ΔhpdC and 630ΔermΔhpdC to 0.1% p-cresol compared

to their respective parent strains (Figure 4C), however, the R20291 strains (wild-type and R20291ΔhpdC) are significantly more tolerant to p-cresol than their 630 counterparts (wild-type and 630ΔermΔhpdC) (p < 0.01). The absence of p-cresol production observed in the R20291ΔhpdC and 630ΔermΔhpdC mutants by NMR spectroscopy in rich media supplemented with 0.1% p-HPA (Figure 4A), was reproducible in minimal media using zNose™ gas chromatography (data not shown). Figure 4 Analysis of the decarboxylase mutants. A) NMR spectra showing p-cresol production in BHI broth supplemented with 0.1% p-HPA for parent and mutant strains, B) Growth curve of the R20291ΔhpdC and 630ΔhpdC mutants compared to respective parent strains. C) Tolerance to 0.1% p-cresol of ΔhpdC mutants and respective parent strains. Temporal production of p-HPA and p-cresol in mutant and parent strains Preliminary NMR spectroscopy revealed that p-cresol was produced in unsupplemented minimal media

(YP broth), indicating that the available tyrosine was converted to p-cresol via the intermediate p-HPA. The temporal production of p-HPA and p-cresol were assessed in minimal YP media, using both wild-type and mutant strains of R20291 and 630Δerm. For each strain, samples were taken every hour for the first 8 hours with a final time point of 24 Protein tyrosine phosphatase hours, after which the relative production of p-HPA and p-cresol were determined by NMR spectroscopy, the combined data for all the strains and controls is presented in Figure 5A. High levels of tyrosine were present in all samples including the media control (Figure 5A); however, the conversion to p-HPA and p-cresol across all the strains was limited to a few samples (Figure 5A), namely the latter time points in the parent strains. In the decarboxylase mutants R20291ΔhpdC and 630ΔermΔhpdC, a build up of p-HPA was evident from 4 to 24 hours (Figure 5B and 5C). The level of p-HPA production was significantly higher in the R20291ΔhpdC mutant compared to the 630ΔermΔhpdC mutant (Figure 5B and 5C). As predicted, p-cresol was not detected in the mutant samples.