TABLE 1.

Carbon isotopic composition of CO₂ and CH₄ of culture and coculture experiments

Growth condition	Initial H2 (aqc ) (μM)	δ13C value (‰)			εCO2-CH4 (‰)
		CO2 (aq)		CH4, Tf
		To	Tf
M. jannaschii only
Chemostat R1	83	−35.1	−29.0	−55.9	28.5
Chemostat R2	80	−34.6	−28.2	−55.9	29.3
Chemostat R3	80	−35.2	−28.4	−55.8	29.0
Chemostat R4	18	−35.9	−33.3	−75.7	45.9
Chemostat R5	15	−35.7	−31.8	−74.2	45.8
Chemostat R6	27	−35.8	−32.0	−72.5	43.7
Bottle B1	1,200a	−26.1	+22.6	−32.9	22.1b
Bottle B2	1,200a	−26.1	+19.2	−34.2	23.0b
M. jannaschii-T. paralvinellae coculture
Bottle B3 (formate)	0	−26.7	−22.8	−99.4	85.1
Bottle B4 (formate)	0	−26.7	−23.0	−99.4	84.8
Bottle B5 (maltose)	0	−25.5	−24.4	−91.2	73.5
Bottle B6 (maltose)	0	−25.5	−21.6	−89.0	73.9

^aEstimated at 82°C using the Geochemist’s Workbench Standard 10.0 (Aqueous Solutions, LLC, Champaign, Illinois, USA).

^bCalculated based on the isotopic compositions of the starting CO₂, final CO₂, and accumulated methane.

^caq, aqueous concentration.