FIGURE 4.

Average total CH₄ production in 2015 microcosms. The microcosms were incubated at 80°C (A) and 55°C (B) and amended with 200 kPa of H₂:CO₂ (red); 200 kPa of N₂:CO₂, 0.5% tryptone and 0.01% yeast extract (green); and 2 kPa of H₂ and 198 kPa of N₂:CO₂ (black). The sample bars represent the range of the duplicate incubations. The asterisks show where there was growth in only one microcosm bottle.