麹菌の自然変異に関する研究-13-
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概要
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Heterocaryotic combinations have been worked out with the mutants of Asp. sojae, carrying colour and nutritional markers: i.e. Y leu Y arg, Al leu and Al his. Stable green strain (G) were obtained in the following combinations: Y leu+Al his, Y arg+ Al his, and Y arg+Al leu, the properties of which are as follows: They had heads of uniformly green conidial chains like the original wild type Asp. sojae K. S. They were able to grow on minimal medium. On Koji-agar or a synthetic medium supplemented with either one or both of the amino acids required by the component strains, they exhibited homogeneous green colonies, instead of segregating out into Yellow- and Albino-types sectors as is in the case of heterocaryons. They were exceedingly stable and persisted 99.5% as green colonies. After 10_??_14 day's incubation, they rarely produced heads, small spots or sectors of either component colours. The segregants which occurred from the G through pedigree-culture are as follows As to the colour marker, 0.3_??_0.5% Yellow- or Albino-type segregants occurred. Among these segregants, Yellow type ones still segregated into Albino-type at an extremely- low ratio (0.1_??_0.3%). In concerning the nutritional marker, the G were prototroph and Yellow- or Albino-type segregants were prototroph or the same requiring as the component strains. However, in the combination of (Y arg+Al leu), two new Yellow segregants have been obtained which differ from the component strains. Finally, a method for increasing frequencies of occurrence of stable green strains (G) has been deviced. The conditions effecting the increase are as follows: The frequency of the spontaneous occurrence of G differed according to the sort of combinations of the component strains, ranging one G per 1000_??_2500 heterocaryons (0.2_??_3 G per 106 plated conidia). For obtaining the G, camphor treatment was somewhat effective but acenaphthene treatment was not effective. The frequency of the occurrence of G was raised to 2_??_9 G per 102 plated surving conidia by UV-irradiation. Thus UV-irradiation increased the frequency of the G production by 104 times more than those which were not treated.
- 社団法人 日本農芸化学会の論文