抄録
(1) This investigation is concerned with the mutagenic action of the nitrogen mustard, methyl-bis-beta-chloroethylamine on the Aspergillus sojae of soy making. A study was made of morphological mutations.
(2) It was found that nitrogen mustard treated spores germinated slower than the controls, which germinated within 48 hours in the case of untreated 7 days old spore.
(3) It was found that spores of Aspergillus sojae were susceptible to nitrogen mustard, namely almost all the spores were killed at 0.01M concentration in 20 minutes but they were not killed at 0.005M concentration completely in 30 minutes.
(4) The mutation rate increased linearly with nitrogen mustard treatment as in X-ray irradiation and mutation rate of approximately 30% were obtained at 0.01M concentration, but in the case of ultraviolet radiation mutation rate reached a peak and then declined. Nitrogen mustard was recognized as very effective in producing mutations as in the case of ultraviolet.
(5) The author observed in this experiement as follow &: Lots of olive; light, sterile and restricted types were obtained as mutant. In almost cases light type strains were unstable, but olive type strains were rarely unstable. There was no evident connection between morphological mutation ratio and frequencies of mutant types. Frequencies of biochemical mutants were extremely few.
