Table 1.

CO uptake observed for A. ehrlichii MLHE-1 incubated with varied electron acceptors (suboxic, 0.2% O₂; anoxic, +5 mM nitrate) or magnesium perchlorate (50 mM) or magnesium sulfate (500 mM)

Uptake units	Treatments
	Oxic	Suboxic	Anoxic
Rate, nmol−1·mgdw−1·h−1	1.61 ± 0.39	1.49 ± 0.26	0.23 ± 0.03
	Control	Mg(ClO4)2	MgSO4
Rate, nmol−1·mgdw−1·h−1	0.49 ± 0.07	0.52 ± 0.05	0.63 ± 0.09
	Control	Vacuum control	10 mbar
Rate constant, h−1	0.91 ± 0.04	1.25 ± 0.31	0.67 ± 0.16

Uptake rate constants (h⁻¹ ± 1 SE, n = 3) were observed for ambient and low-pressure incubations. Rates for varied electron acceptor and magnesium salt availability [nmol (mg cell dry weight)⁻¹⋅h⁻¹ ± 1 SE, n = 3] were determined for cells incubated with initial headspace CO concentrations of 8 ppm and were based on first-order uptake rate constants. Rate constants for varied pressure incubations were obtained for treatments initiated at 6 ppm CO and 1 atm pressure (controls), for treatments with 6 ppm CO and 1 atm pressure reestablished after reducing pressure to 10 mbar (vacuum controls), and for treatments with 600 ppm CO at 10 mbar pressure. mgdw, mg cell dry weight.