In the present paper, the inhibitory effects of Antimycin-A (Antipiriculin, AP), Blastmycin (BM), and Phenyl mercuric acetate (PMA) on the fundamental metabolic systems of P. oryzae are reported. The enzyme solution of P. oryzae was able to oxidize some organic acids found in TCA cycle, and this oxidation, especially that of succinate or lactate, was remarkably inhibited by AP, BM, and PMA. The endogenous respiration of the enzyme solution, however, was not inhibited by these inhibitors, but was inhibited by a high concentration of PMA. As to the terminal respiratory systems in P. oryzae, the following series of hydrogen doner and acceptor systems were presented, that is, succinic dehydrogenase, succinoxidase system, and cytochrome oxidase system. Both AP and BM showed definitely a specific inhibition to the succinoxidase system, whereas PMA inhibited all these systems. The oxidative phosphorylation and glycolysis in P. oryzae were also found not to be affected by AP and BM, although PMA seemed to inhibit the glycolysis slightly.
This paper describes the nitrogen metabolism of P. oryzae and its inhibition by Antimycin-A (AP), Blastmycin (BM), and Phenyl mercuric acetate (PMA). According to the rate of growth of P. oryzae, the various nitrogen sources tested were divided into three groups. The most suitable group for fungal growth contains, for instance, glutamic acid, aspartic acid, serine, leucine, NH4Cl and so on. The amino acids belonging to the most suitable group were oxidized by P. oryzae in a short period of incubation, and the most of these oxidation was completely inhibited by AP, BM, and PMA. Two types of transamination were found in P. oryzae. One of these reaction was that of between α-ketoglutaric acid and alanine, and another was between α-ketoglutaric acid and aspartic acid. In the case of cell level, the former reaction was completely inhibited by AP, BM, and PMA at 18 hours after incubation, while the latter was moderately inhibited even by PMA. Using the extracted enzyme solution, however, no inhibitory effects of both AP and BM on these two reactions were confirmed, although a strong inhibition was detected by PMA.
(1) Blasticidin S は稲熱病菌胞子の発芽ならびに形成に対し酢酸フェニール水銀とほぼ同程度の阻害効果を示した。また菌糸生育に対しては酢酸フェニール水銀に優る著しい阻害効果を示した。但し寒天培地中では稲熱病菌の生育を阻止するのに Blasticidin S は酢酸フェニール水銀よりも多量の薬量を必要とした。寒天培地中では Blasticidin S の効果は低下すると思われる。 (2) 植物体中の Blasticidin S はトマト葉かび病菌を被検菌とした薄層検定法により0.1μg/mlの濃度まで定量することができた。 (3) 稲葉上では日数の経過とともに次第に抗菌力価は低下した。また稲苗の地際部の茎に軟膏を塗布した後24時間以内に上部の茎葉に生体重1g当り30μg前後の浸透・移行量がみられた。 (4) 温室内稲苗接種試験で Blasticidin S は稲熱病菌接種前に散布された場合にはその葉稲熱病防除効果は酢酸フェニール水銀に劣つたが, 接種後に散布した場合には酢酸フェニール水銀に優る治療効果を示した。これは Blasticidin S が本菌菌糸に対し著しい生育阻害効果を有するので葉上で病斑の進展が阻止されるためと思われる。