Fig. 5
Simulations with the three-species model (D. vulgaris, M. maripaludis, and M. barkeri) for growth on ethanol. a–c show optimality degree OptDeg for the maximum community growth rate (0.0505 h−1) calculated for different community compositions. Three scenarios were simulated: a competition scenario: both methanogens can only use the hydrogenotrophic pathway for methanogenesis. b Use of hydrogenotrophic pathway for M. maripaludis and acetoclastic pathway for M. barkeri c use of hydrogenotrophic pathway for M. maripaludis and hydrogenotrophic and acetoclastic pathway for M. barkeri. F DV: biomass fraction of D. vulgaris; F MM: biomass fraction of M. maripaludis. We used ATPmaint = 4.3 mmolATP/gDW/h for D. vulgaris, ATPmaint = 0.9 mmolATP/gDW/h for M. maripaludis and ATPmaint = 2.5 mmolATP/gDW/h for M. barkeri. For scenario c the minimum methane production rates (d) and minimum methane yield (referred to ethanol) (e) were also calculated