ABSTRACT
When suddenly exposed to air the growth of the obligate anaerobic bacterium of the bacteroidaceae type, strain B6, continues for a few hours before coming to a complete stop. When air is shut off soon after growth has ceased, the organism is able to reestablish anaerobic conditions due to an ability to reduce O2, and resumes normal growth after another few hours. The O2 reducing ability of the organism is due to the presence in the cells of a particle-bound NADH oxidase, a soluble NADPH oxidase and a soluble pyruvate oxidase. The two pyridine nucleotide oxidases reduce O2 to H2O2, the pyruvate oxidase reduces O2 to H2O. Catalase and peroxidase were not detected in anaerobically grown cells. Kinetic studies with cell-free extracts showed that the pyruvate oxidase had a considerably greater affinity (smaller Km) for O2 and capacity (higher Vmax) for O2 reduction than the two other oxidases. It is postulated that the pyruvate oxidase acts as a scavenger for O2, leading to the non-toxic reduction product H2O, and thus functions as a defense mechanism against oxygen toxicity when the organism is exposed to aerobic condition.
Subject(s)
Air Microbiology , Bacteroidaceae/growth & development , Oxygen/metabolism , Anaerobiosis , Bacteroidaceae/enzymology , Bacteroidaceae/metabolism , Culture Media , Fermentation , Glucose/metabolism , Kinetics , Multienzyme Complexes/metabolism , NAD/metabolism , NADH, NADPH Oxidoreductases/metabolism , NADP/metabolism , NADPH Oxidases , Oxidation-Reduction , Pyruvate Oxidase/metabolism , Pyruvates/metabolismABSTRACT
Vers le milieu du XIXe siècle, la l`pre fut très répandue en Norvège. C'est surtout depuis cette époque que l'attention des autorités se porta sur cette maladie. En 1854, un médecin inspecteur pour le contrôle de la lèpre fut nommé. Dans les communes ou régnait la maladie, les conseils sanitaires, présidés, par le médecin cantonal, furent établis en 1875.
