Fig. 4

CH₄ production, MER, and turnover rate of M. okinawensis under Enceladus-like conditions at high pressure. Biological CH₄ production determined by gas chromatography (blue) (Vol.-% h⁻¹) and turnover rates (h⁻¹) (green) and MER·10 (mmol L⁻¹ h⁻¹) (red) measured from headspace gas conversion using M. okinawensis (experiment 1 in light colours, experiment 2 in dark colours) under putative Enceladus-like conditions in a 2.0 L bioreactor (for detailed medium composition, see Supplementary Table 3 and for detailed gas composition see Table 4, n = 2). The positive control experiment contained also the liquid inhibitors but only H₂/CO₂ (4:1) in the headspace. For high-pressure experiments without any inhibitors see Supplementary Fig. 2