Figure 2.

Solution pH of replicate laboratory reactors. After biofilm establishment at ∼pH 1.4, three ¹⁵N-labeled reactors were lowered to an average pH of 0.85 (day 0). pH treatments were maintained over a 19-day period, after which communities were sampled for proteomic analyses. Fresh medium was re-supplied on days 5, 9, 13 and 16.