Isolation and Characterization of a Bacillus subtilis Strain Producing Natto with Strong Umami-Taste and High Viscosity.

概要

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Natto is a non-salted fermented soybean food in Japan. Some Bacillus subtilis strains (formerly called "B. natto") are utilized for producing natto. In natto production the bacteria growing on steamed soybeans hydrolyze soybean proteins to peptides and amino acids and synthesize viscous material (r-polyglutamate) which is characteristic of natto. To produce natto with strong umami-taste, B. subtilis strains with high activity of protease were screened from soil, harvested rice plant and so on. A strain NN-1 was selected out of 295 strains tested, because of its high activity of protease in the growing broth (121 U/ml) and ability of producing natto both with strong umami-taste and large amount of viscous material. In the presence of phytone, the liquid culture of strain NN-1 was more viscous than that of a commercial strain. Strain NN-1 also produced more γ-glutamyltranspeptidase (1060international unit/l), which was thought to be a key enzyme in γ-polyglutamate synthesis. StrainNN-1 was identified as B.subtilis. The natto produced by strain NN-1 contained about twice free amino acids of the natto produced by a commercial strain and showed higher scores in sensory evaluation.
社団法人日本食品科学工学会の論文