Fig. 2: Metabolite levels in P. putida KT2440 under oxidative stress.
a Relative abundance of selected metabolites, grouped according to the biochemical block they belong to (i.e. PP pathway, EMP pathway, and TCA cycle). Relative metabolite abundance is expressed as the ratio between H2O2-induced oxidative stress and control (Ctrl.) conditions, derived from summed ion abundance of all isotopes (counts). Data from experiments in the presence of [1-13C1]- and [6-13C1]-glucose (Glc.) are averaged. Bars represent the mean value of metabolite abundance ± standard deviations obtained in triplicate measurements of samples from three independent experiments per labeled substrate. Statistical comparisons between the metabolite abundance ratios (with a ratio = 1 indicating no difference between stressed cultures and control experiments) were assessed by the Student’s t test with Welch’s correction. Single (*) and double asterisks (**) identify significant differences at the p < 0.05 and p < 0.01 levels, respectively. Actual p values for the metabolite ratios in the PP pathway (stressed versus control experiments) were p = 0.0052, 0.0031, 0.0092, 0.0043, and 0.0055, indicated in the same order as the bar graph. For the metabolites in the EMP pathway (stressed versus control experiments), the values were p = 0.0198, 0.0083, 0.0079, and 0.0412. For the metabolites in the TCA cycle (stressed versus control experiments), the values were p = 0.0322, 0.0049, 0.0931, and 0.0074. b Changes in selected metabolic flux ratios in upper metabolism upon exposure of the cells to H2O2. The 13C-labeled substrate used in each experiment is indicated. Bars represent averages from three independent experiments, and standard deviations were calculated using the covariance matrices of the respective mass distribution vectors by applying the Gaussian law of error propagation. c Relative pathway contribution to the G6P and F6P pools. The input of each of the metabolic pathways to the sugar phosphate pool under oxidative stress conditions is indicated with different colors. All abbreviations used in this figure are as indicated in the legend to Fig. S1. CDW, cell dry weight.
