Effects of the dctA::spc mutation on growth. Cultures were grown aerobically in M9 salts medium containing 0.4% glucose (A), 50 mM succinate (B), 50 mM malate (C), or 50 mM fumarate: AN387 (dctA+) (□), MDO800 (dctA::spc) (▵), AN387(pDctA) (■), and MDO800(pDctA) (▴). OD650 nm, optical density at 650 nm.