菌類の器官形成についての研究は, そのほとんどが形態の観察ならびに代謝産物の増減に関するものであって, 形成機構を制御する見地からのものはまだ数少ない。筆者らはPhytophthora capsiciの無性あるいは有性生殖器官の形成について引き続いて研究を行なっているが, この制御機構の研究のために形成刺激が随時に与えられ, また除かれるような手段が必要になってきた。刺激方法はいろいろとあるが菌の方の反応の速やかさという点から細菌によるP. capsiciの遊走子のうの形成促進効果を指標とすることにした。この細菌による形成刺激を希望する時点でとり除くために抗生物質を用いることにしたが, この物質は1) P. capsiciの発育を阻害しない, 2) P. capsiciの遊走子のうの形成能力を低下させない, 3)遊走子のう形成刺激能力をもつ細菌を速かに殺すか, その刺激機能ををいちじるしく低下せしめる, などの3つの条件を満たさねばならない。Penicillin G Na-salt, Polymyxin B sulfate, Vancomycin HCl, Dihydrostreptomycin sulfate, Chloromycetin, Cycloserine, Spiramycin, Gentamicin, Kanamycin, Colistin及びPentrexについて濃度を変えて刺激除去剤としての効果を検討した結果Pentrexが比較的よく上記3条件を満し, 使用濃度も1250ppmでよいことが判った。Regulatory system on the sporulation of fungi was investigated in Phytophthora capsici LEON. with referrence to the application of antibiotics For the induction of sporulation it is necessary to utilize adequate stimulants and inhibitors. Light stimulation is not suitable for this study, because the morphological change in the fungus proceeds too slowly after irradiation. By the same reason, temperature regulation and the dilution of nutrition in culture media are not unfavorable. On the contrary bacteria, SPB-3,inoculated together stimulate sporulation of the fungus rapidly and zoosporangia are formed completely within 120-150 min after contact with the bacterium. For furthee study it is desirable to get the substances which stop the bacterial stimulation to the fungus whenever occasion arises. Therefore, effects of some antibiotics on the growth of P. capsici and SPB-3 were investigated in regards to following 3 conditious to be required : 1) hyphal growth of P. capsici is not inhibited by antibiotic substance and 3) stimulatory bacteria for sporulation are killed or the stimulatory function is destroyed by the substance immediately after the substance is added to the fungal colony. Penicillin G Na-salt Polymyxin B sulfate. Vancomycin HCl, Cycloserine, Colistin, Spiramycin, Dihydrostreptomycin sulfate, Kanamycin, Chloromycetin, Gentamicin, and Pentrex are tested in line with conditions described above. In Penicillin G Na-salt, P. capsici grow well at concentrations tested, but the sporulation ability is reduced with ncreasing concentration and SPB-3 is not killed even at high concentration. In Polymyxin B gulfate, the growth of P. capsici is not inhibited so markedly, but the sporulation ability of the fungus is reduced at high concentration. In Vancomycin HCl, Cycloserine, Colistin and Spiramycin, SPB-3 is not killed. In Dihydrostreptomycin sulfate, the growth of P. capsici is completely inhibited even at low concentration, but resistant mutants are grown frequently. In Kanamycin, P. capsici don\u27t grow. In Chloromycetin and Gentamicin, the fungus don\u27t grow well. In Pentrex, P. capsici grow well at high level and the sporulation ability of the fungus is not lost. In addition SPB-3 is killed at high concentration. From these result on 3 conditions mentioned above, Pentrex 1250 ppm is recommended for the study of the regulatory system of the sporulation of P. capsici
