Fig. 2

Methane yield per g carbon [mL CH₄ g⁻¹ TC] during (a) and at the end of (b) 28 days of mesophilic incubation from reactors reflecting different overload conditions (low, medium, high). Cont control, Tryp tryptophan, Tyr tyrosine, Phe phenylalanine, ME meat extract, Cas casein. *Significantly different from control: conover test. α = 0.01. H₀ rejected if p ≤ α/2