Fig. 2.

H₂ gas accumulation during the enrichment of terrestrial (a, c, e) and marine (b, d, f) cultures using molasses. Cultures were tested in batch and had different initial pH values (pHi) (either 6 or 7) and organic loading rates (OLR) (either 1 or 5 g_COD L⁻¹ d⁻¹, equivalent to an initial content of 7 or 35 g_COD L⁻¹, respectively). Temperature was set to 35 °C. Cultures were tested for 7 days, after which 10% liquid volume was withdrawn and incubated again with fresh medium for another 7 days. Hence, the enrichment consisted of 3 consecutive batches of 1 week each. Marine cultures were provided with 23 g L⁻¹ NaCl to maintain their original salinity in all conditions. Error bars represent standard deviations of 3 independent biological replicates. Keys reported in the graph