カビ胞子の発芽における代謝生理(第2報) : 発芽過程における耐毒性獲得現象

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Spores of Aspergillus Oryzae suspended in a germination medium (TERUI and MOCHIZUKI : Technol. Rept., Osaka Univ., 5,219,1955) containing 0.002〜0.005M As_2O_3 could germinate and grow normally or after a short period of lag, while the growth of germinated cells or young mycelia grown in the absence of As_2O_3 was inhibited strongly on addition of the same drug. The earlier the time of addition of the drug was, the less was the degree of inhibition in both germinination and growth. Metabolic filtrate from the suspension containing young mycelia developed in contact with the above drug was so strongly poisonous to young mycelia grown in the absence of the drug, that the secretion of antagonistic substance or decrease in drug concentration could not explain the cause of the above phenomenon. Microscopic observation revealed that almost all the viable spores could swell and germinate in the above experiment with As_2O_3 added in earlier phase.These facts seemed to present strong evidence for a mass adaptation or adaptation at the cellular level. One of the difficulties encountered in demonstrating mass adaptation to resist drugs in the case of bacteria may consist in the inexact exclusion of a chance permitting selective multiplication of pre-existing resistant mutant during a course of experiment. In our case, the spores acquired remarkable resistance against the drug before fully germinated, therefore such a difficulty could be eliminated.Spores of Asp. niger and Pen. purpurogenum also behaved similarly. Such an adaptation could be observed also with NaF (M/100) and NaN_3 (M/5000), but not with phenol. Cross-resistance was demonstrated between arsenate and arsenite, but not between other drugs dealt with. Growth in post-germination phase went on normally in the presence of M/500 As_2O_3 when pre-germnination phase had been developed in contact with M/2000 As_2O_3 a sub-inhibitory concentration for the post-germination phase. Adapted young mycclia lowered their resistance level, i.e. became de-adapted, slowly during the course of growth without the drug.Mass adaptation in the above sense was observed only when growth (swelling) of spores had occurred in contact with the above drugs.
社団法人日本生物工学会の論文
1958-08-15

カビ胞子の発芽における代謝生理(第2報) : 発芽過程における耐毒性獲得現象

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