FIG 1.

Relative abundances of Actinobacteria (a), Bacteroidetes (b), Alphaproteobacteria (c), Betaproteobacteria (d), Acidobacteria (e), and Gammaproteobacteria (f) across the pH gradient. The relative abundances of Actinobacteria and Bacteroidetes positively correlated with pH; the abundances of Alphaproteobacteria, Betaproteobacteria, and Acidobacteria decreased with pH; Gammaproteobacteria showed no significant relationship with pH. The formulas, R² values, and significances are given in each panel.