酵母によるアントラニル酸よりトリプトファンの酵醗生産(第5報) : Hansenula属の栄養要求変異株によるトリプトフアンの形成

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With a view to obtaining strains of improved breed for tryptophan production, studies have been commence with auxotrophic haploid mutants derived from thue original auxoautotrophic diploid strain, H095,of Hansenula sp.Firstly, a number of auxotrophic haploid mutants were obtained by ultraviolet irradiation from haploids isolated by modified Wickerham's method. Out of these strains, were selected those capable of producing fast growing prototrophic hybrids when inoculated in coupled combinations with mutantrs requiring different growth factor.These selected mutants are thought to be available not only for (1) genetic studies leading to the improved yield of tryptophan, but also for (2) obtaining auxotrophic diploids with which tryptophan production is expected to proceed "preferentially" under conditions of limited growth. (List of mutants obtained : cf. Fig. 1〜3; examples of mating experiments : cf. Table 2).Secondly, in connection with the possibility mentioned under (2), preliminary experiments were carried out on growth and tryptophan production in "shift-down" cultures of these mutants with or without supplemented growth factors. In some instances, tryptophan production was remarkable despite that growth was strongly suppressed owing to the deficit of requiring growth factor. Especially, three histidineless and one methionineless mutants were of interest; these mutants could accumulate tryptophan in higher amounts in "shift-down" cultures with the deficient medium than with the supplemented media.It was observed, in addition, that some of the prototrophic clones arosen from the above-mentioned mixed cultures of dificient mutants produced small colonies and small cells such as those of haploid strains. Elucidation of this phenomenon awaits further research. Implications of the above results are discussed in relation to the future imprivement of tryptophan yield and in conjunction with the recent yield which is approaching a level of 6 g/l, obtained by improving culture conditions.
社団法人日本生物工学会の論文
1963-10-15

酵母によるアントラニル酸よりトリプトファンの酵醗生産(第5報) : Hansenula属の栄養要求変異株によるトリプトフアンの形成

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