To make a methionine rich feed with the potato starch waste product, a study on the methionine synthesis by the Aspergillus oryzae and its mutants was carried out through the synthetic and potato starch waste product media. The strains 11021 and C₁ 302 F₁ were selected as the methionine productive strains from fourty strains and mutants which were induced by one of the authors.
The addition of metal ions and yeast extract, as the Vitamin B_(12) source, show little effect to the methionine synthesis, but good response to the growth of the strains. It was cleared, however, that the methionine synthesis was markedly enhanced in the potato starch waste media in which formaldehyde, as C₁ unit, was added together with folic acid, metal ions and yeast extract, as the cofactor.
The percentage of the methionine to the pure protein of the fermentated potato starch waste feed increased to 2.10 from 0.15. The maximum utilization of the ammoniacal nitrogen into the mycel protein was 78%.
In view point of the effect of C₁ unit and Pteroyl glutamic acid to the methionine synthesis, it was assumed that Aspergillus oryzae might synthese methionine similar to Escherichia coli and Nenrospora crassa.
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