黒斑病甘藷の病理化學的研究

(第13報)黒斑病菌の呼吸とTerminal Oxidase

抄録

1. Respiratory system particularly cytochrome oxidase system of Ceratostomella fimbriata was studied with intact cell suspension and disintegrated mycelial extract as enzyme sources.
2. Presence of cytochrome oxidase was demonstrated by strong inhibition of cytochrome c oxidation of mycelial extract with KCN, NaN₃ and CO. CO inhibition was photoreversible. Succinate was oxidized also by mycelial extract. Existence of cytochrome a, b, c in the intact cell was clearly demonstrated spectroscopically.
3. Hydroquinone and several other substances were oxidized by laccase in mycelial extract and the experiments on its inhibitory action were done. Phenylthiourea inhibited laccase in about 20% at the strength of 20μM.
4. Cytochrome oxidase activity was almost localized in the insoluble particle sedimented by super centrifugation (10000×g, 30 min). On the other hand, laccase was present in the super-natant.
5. Cytochrome oxidase was more active at early stage of culture, while laccase gradually became active with the development of dark brown color of mycellium.
6. Cytochrome oxidase and laccase of the mutant was compared with those of the normal type. The former activity was about the same, but the latter was very lower.
7. The effects of ipomeamarone and umbelliferon on the respiratory system and terminal oxidase (cytochrom oxidase and laccase) were studied. In vitro experiment, their effects were not evident but the former inhibited strongly the spore respiration and the latter slightly. Physiological and phytopathological meaning of their effects was discussed.