Fig. 1

Growth impairment of C. glutamicum AROM3 due to tyrosol supplementation (A) and tyrosol degradation test (B). AROM3 was cultivated in 1 mL CGXII minimal medium containing 40 g/L glucose, and varying tyrosol concentrations ranging from 0 to 65 mM. The backscatter was measured in a BioLector cultivation system and used to calculate the specific growth rate (green triangles), maximum Δbackscatter (grey circles), and lag phase (red diamonds) for the AROM3 cultures exposed to different tyrosol concentrations (A). The tyrosol concentration leading to a half-maximum growth rate could be estimated from the regression line to be 22 mM, as indicated by the green dotted line. Tyrosol concentrations determined at the beginning and the end of cultivation in the cultures containing 20 mM tyrosol were not significantly different (n.s.: p > 0.05) according to calculation with a two-sided Student’s t test (B). Values and error bars represent means and standard deviations of triplicate cultivations