FIG. 2.

Native PAGE formate dehydrogenase activity. S. meliloti strains were grown in defined medium containing 5 mM bicarbonate and 60 mM formate. Gels were stained for dehydrogenase activity with either the absence of formate and the presence of NAD⁺ (A) or the absence of NAD and the presence of formate (B). Lanes 1, SmA818; lanes 2, Rm1021. The arrow indicates an activity band that is formate dependent and NAD⁺ independent. Equivalent amounts of protein were loaded in all lanes.