Fig. 2.

DFA for sample visualization (controlled contamination). GC-MS metabolite data successfully distinguished samples from contaminated versus noncontaminated microalgal flasks. Projections of the log-transformed intracellular metabolite data from 56 samples into 3D space show three distinct clusters of the three data classes. For each sample, the projection values were calculated as the linear combination of metabolite values determined by DFA. Only metabolites that were detected in more than 25% of the samples for each data class were used for the analysis. Black, samples from flasks contaminated by P. aeruginosa (t = 6 h to t = 24 h); red, samples from flasks contaminated by B. subtilis (t = 6 h to t = 24 h); dark green, samples from noncontaminated microalgal flasks; light green, samples collected from contaminated flasks at time zero.