FIG. 6.

Anaerobic growth of METR-1 and MR-1(pACYC184) using fumarate as the electron acceptor. Two variations of media were compared: M1 medium (pH 7.4) with 15 mM lactate, 20 mM fumarate, and either tetracycline (16 μg ml⁻¹) or chloramphenicol (35 μg ml⁻¹) (M) and M1 medium (pH 7.9) with 30 mM lactate, 2 mM fumarate, and either tetracycline (8 μg ml⁻¹) or chloramphenicol (30 μg ml⁻¹) (SN). SN refers to conditions reported by Saffarini and Nealson (41). METR-1 was not examined with chloramphenicol because it is Tc^r only.