麹菌の自然変異に関する研究-5-
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概要
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The environmental effects upon anastomosis of Koji-molds have been studied by means of hanging drop culture and mixed point-inoculum plate culture, using the color mutants of Asp. sojae. (1 and 2) 1) The lower concentrations, i. e. about 1/10 of ordinary concentrations, were generally-favorable upon various natural media, such as Koji-, Malt-, Rice germ-, and Yeast-extracts. The frequency of anastomosis seems to be accerelated by poor nutritional conditions. 2) Upon the synthetic media (Czapek solution), from 1/2 to 1/20 of the original concent-rations gave good results. Any significant effects could not be recognized through changi-ng the concentrations of KH2PO4, KCl, and MgSO4 in Czapek solution. 3) The optimum concentrations of NaCl, glucose, and lactose, in distilled water were 0. 1 mol., 0.2 mol. and 0.1_??_0.5mol. respectively. Higher or lower osmotic pressures have been. found to be less favorable. 4) The higher C/N ratio generally favours anastomosis especially when the contents of N-source in the media are low to definite extent. 5) The range of the optimal pH zone was rather narrow, i. e. from 5.4 to 6.0. The ability of anastomosis decreased rapidly at the lower, and slowly at the higher side of the optimal zone and was completely inhibited at pH 4 and pH 8.8. 6) The age of the inoculum cultures upon Koji-extract agar at 30° does not give any significant influence upon anastomosis in the extent of from one week to three months. The-inoculum of older cultures, for instance, 7 months, seems to decrease the frequency. 7) The optimum temperature for anastomisis lies in between 25° and 30° which are som-what lower for the optimum growth of the molds.
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