クロカビ糖化酵素生産培養の菌令と多段連続培養における over-ageing 現象について(生物化学工学特集号-II 滅菌および培養工学)

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In the preceding report, were described the phenomena of lag and tailing of glucamylase-producing activity with mycelia transferred from a vessel to the next in three-stage continuous culture.In the nongrowth-associated enzyme production, starvation of adenine-group substances, which resulted in the lowering of μ, was correlated closely to the glucamylase-producing activity (ε) of the mycelia of adenine-requiring mutant (U20-2-5) employed.In shift-down cultures conducted with mycelia harvested at intervals from a growing culture, were measured the average activities (μ^^-_s;ε^^-_s) of mycelia in the initial 4 hours and the relative maximum increment of mycelial weight (X_p), ω=(X'_m-X_p)/X_p.The value of ω was shown to be proportional to μ_p (μ of mycelia in the pre-culture at the time-point of replacement) or to μ^^-_s, and correlated to ε^^-_s according approximately to the expression : ε_^^-s=ε'_m-B'ω.Thus, the relationship, ε^^-_s≌ε'_m-Cμ^^-_s, was naturally maintained.Therefore, ω could represent the "immaturity" of mycelia, and the physiological age of mycelia would be expressed in terms a function of μ or ε.For instance, (ε_m-ε)/ε_m in pre-cultures as well as in shift-down cultures could represent the degree of immaturity, as this was proportional to ω. Also, the value of ε/ε_m, which was a linear function of μ or ω, would represent the age of mycelia in cultures of this type.In the case where shift-down cultures started with fully maturated mycelia were fed continuously or semi-continuously with adenine-free madia while mycelia were retained in the culture, enzyme-producing activity (ε_μ) fell gradually off from its initial value(〜ε_m).As a measure of over-ageing, the quotient(ε_m-ε_μ)/ε_m was used which was increased with time.In order to maintain the high activity for a long time in shift-down or the 3rd stage continuous culture, adenine feeding at an adequate rate (e. g. 4μM/hr/25mg mycelia) was necessary.When the rate was increased further, the activity was decreased as the mycelia became younger, i. e. immature with respect to glucamylase production.Thus, the degree of immaturity became greater as the rate of adenine feeding was increased.Over-ageing did not result in the decreased DNA content, but caused the lowering of RNA content. Under the optimal feeding of ^14C-adenine, RNA, ATP and GTP became incorporated with radioactive adenine while DNA remained in the original state; these results indicated that the optimal rate of adenine feeding was effective in filling up the turn-over loss of RNA and some nucleotides.Guanine, which was ineffective in supporting growth as a substitute of adenine, seemed to be only partly effective for preventing over-ageing; this could be incorporated into RNA to some extent in nongrowing shift-down culture.
社団法人日本生物工学会の論文
1965-08-25

クロカビ糖化酵素生産培養の菌令と多段連続培養における over-ageing 現象について(生物化学工学特集号-II 滅菌および培養工学)

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