工業微生物の対酸素挙動の解析 III : Bacillus amylosolvensの増殖ならびに水解酵素生産におよぼす溶存酸素の影響

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1. The time-course of metabolism of Bacillus amylosolvens, an useful organism for producing amylase and protease by submerged culture, can roughly be devided into two phases, namely proliferating phase (earlier phase) and hydrolase-produciong phase (later phase) as hown in Fig. 1 and 2.2. The cells in proliferating phase (P-cells) show the MICHAELIS constant, Km, in respiration rate-[O_2] relationship as low as 3.5×10^<-7>M, whereas those of hydrolase producing phase (H-cells) manifested two MICHAELIS constants as analyzed by our method (cf. Technol. Rept. Osaka Univ. 1960) ; in the latter case, one (Km_1) is almost the same magnitude as that of P-cells, and the other (Km_2) in much higher than Km_1,i.e. 3×10^<-4> M (Fig. 3〜4). The oxygen-terminal factor exhibiting Km_1 (or Km of P-cells) is azide-sensitive, while the entity exhibiting Km_2 is azide-insensitive. Experiments with sonic extracts of cells have revealed that P-cells contain more of cytochrome oxidase and cytochrome c than H-cells do, while H-cells contain much more of FAD than P-cells do (Table 1). It is presumed from the above that the oxygen-temrinal factor is cytochrome oxidase almost exclusively in P-cells, which are transformed as the culture is aged, into H-cells having oxygen-terminal flavin enzyme playing considerable part in cell respiration besides cytochrome oxidase (cf. also Table 2).3. Analyses of the time-courses of cultures in which constant levels of [O_2] were maintained throughout indicate that the specific rate of oxygen-adaptation, Sr, is a function of [O_2] obeying MICHAELIS equation (Fig. 6). The saturation constant (Ks) in this equation is 7×10^<-5>M, which is as high a value as that exhibiting the highest specific rate of hydrolase formation (Fig. 9). Almost maximal value of specific gorwth rate, μ, can be attained at an oxygen concentration of ca. 5×10^<-4>M, which permits 88% max.of Sr (Fig. 9). Thus, the saturation concentrations of oxygen for these three activities may be in the following order of magnitude : Sr>μ≫(production of hydrolase-forming system).4. From the above and on the basis of the results of experimnets in which [O_2] is changed in the course of culture (Fig. 10), it is deduced that relatively high [O_2], e.g. 2×10^<-4>M, should be applied in the proliferating phase in order to secure sufficient amount of hydrolase-forming system, but much lower level of [O_2], e.g. 2×10^<-5>M, will do for the production of hydrolases by existing cells.
公益社団法人日本生物工学会の論文
1961-07-15

工業微生物の対酸素挙動の解析 III : Bacillus amylosolvensの増殖ならびに水解酵素生産におよぼす溶存酸素の影響

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