SUMMARY: A streptomycin-resistant strain of , which requires haemin for aerobic growth, grew either aerobically or anaerobically in the absence of haemin provided the medium was supplemented with acetate or pyruvate; growth with these organic acids was increased by uracil and purines. The parent drug-sensitive strain grew aerobically without haemin but when grown anaerobically required either uracil or acetate or pyruvate. With both strains mevalonate replaced acetate and was about ten times more active.

The products of glucose fermentation by both strains showed no gross difference, lactate being predominant (about 85% of the glucose carbon); only small amounts of acetate were detected. Under aerobic conditions suspensions of the parent strain oxidized glucose to acetate which accumulated. The mutant strain oxidized glucose to acetate only when previously grown with haemin or when haemin was added to the suspension of organisms. When the organism was grown with acetate in place of haemin, lactate was the predominant product. The ability of the mutant to form sufficient acetate from glucose for biosynthetic purposes is apparently dependent on a functional electron transport chain involving haemoproteins. A nicotinamide-adenine dinucleotide-linked lactate dehydrogenase and a pyruvate oxidizing system are present in extracts of both organisms. The activity of these enzymes in the mutant strain was similar whether the organisms were grown on haemin or acetate.


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