Fig. 3

Matrix of Pearson’s correlations from pairwise comparisons between consecutive pairs of samples from the bulk solution (S), early anode (E), intermediate anode (I), and mature anode (M), with respect to 392 different OTUs. As specified by the legend, darker colors indicate a higher Pearson’s coefficient and thus more similarity between the two samples compared. A one-way ANOVA on Pearson’s coefficients confirmed that the MFC developmental stages were significantly different (p < 2 × 10⁻⁹)