Aspergillus niger およ び Aspergillus awamori の 醗酵と発芽に関する生理的研究

I. クロカビの浸透価と酸生成との関係

抄録

Surveying the relation between the acid (citric, gluconic and oxalic acid) production and the osmotic pressure of the mycelium in many cases, the following results were obtained.
1. In good acid production, the initial osmotic pressure is as high as 1.6-1.7M.
2. The initial osmotic pressure of the old strain, not pre-cultured and of the nitrogen-mustard treated strain is low.
3. When the osmotic value decreases to about 1.3-1.2mol, the acid production is accelerated and then increases gradually during the period when the osmotic value is 1.0-0.9 M.
4. Optimum concentration of sucrose in basal medium is 10-14%. At the growth stage 10% of sucrose is preferable, while at the stationary stage, 14%.
5. Effects of deficiency and excess of N and K are remarkable, as compared with those of Mg and Fe. It may be said that as in the case of sucrose, a lower concentration of N is preferable at the grwoth stage and a higher concentration of it at the stationary stage.
6. If 1-3% methanol is added in basal medium, the irregular forms of hyphae are observed at the growth stage and in many cases more citric acid is produced. In such cases, citric acid production is more promoted than at the ordinary osmotic value. If we add agar and starch moreover we have much more citric acid production.
7. As an application of this observation, we can have more citric acid production, when the initial concentration of NH₄NO₃ in basal medium is 1% and increases to 2% on the 3rd day.