FIGURE 1.

Unsupervised classification using principal component analysis (PCA) and hierarchical clustering (HCA) on the relative concentration of the 32 metabolites from the 18 cultures (n = 3). Loading plot (A) shows the projection of each metabolite numbered consistently with Table 2. The metabolite coloration corresponds to its chemical family: alcohol (red), aldehyde (magenta), ketone (blue), ester (green), phenol (purple) and saturated fatty acid (yellow). HCA (B) with cut-off enabling a separation in six clusters depicted in the PCA score plot (C) with each cluster associated to one color.