SOME ENZYMATIC CHANGES ACCOMPANYING THE SHIFT FROM ANAEROBIOSIS TO AEROBIOSIS IN PASTEURELLA PESTIS

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Abstract
The terminal respiration of P. pestis, strain A1122, is under adaptive control. The present study defines some of the enzymes involved in the adaptive process. Enzymatically-active cell extracts of aerobically-grown, anaerobically-grown, and anaerobically-grown but aerobically-adapted cells were prepared by grinding packed washed wet cells with alumina. Extracts of aerobically-grown cells have approx. 60 times greater isocitric dehydrogenase activity, 8 times greater aconitase activity, and 4.5 times greater fumarase activity as compared with anaerobically-grown cells. Similarly, aerobically-grown cells possess a cytochrome with an alpha absorption band at 560 m[mu] and contain intracellular hematin, while no cytochrome or only traces of intracellular hematin occurs in anaerobically-grown cells. Aeration in the presence of a casein hydrolysate glucose medium, which converts anaerobically-grown cells to the physiological characteristics of aerobic cells, induces synthesis of these enzymes and causes the disappearance of the characteristic blackening process of anaerobic cells. The cytochrome present in aerobically-grown cells is heat labile, cyanide sensitive, and closely associated with the insoluble portion of the cell. Cytochrome c and cytochrome c oxidase are not present in these cells. Absence of any detectable cytochrome, presence of only traces of intracellular hematin, apparent greater sensitivity to CO (and perhaps to azide), and equal sensitivity to cyanide,indicate that the hydrogen transport system in the primary phase of glucose oxidation in anaerobically-grown cells may involve a metalloprotein quite different from that in aerobic cells.