• DOI:10.1271/bbb.80129
• Corpus ID: 30111356

Identification of Two Major Ammonia-Releasing Reactions Involved in Secondary Natto Fermentation

@article{Kada2008IdentificationOT,
  title={Identification of Two Major Ammonia-Releasing Reactions Involved in Secondary Natto Fermentation},
  author={Shigeki Kada and Masahiro Yabusaki and Takayuki Kaga and Hitoshi Ashida and Ken-ichi Yoshida},
  journal={Bioscience, Biotechnology, and Biochemistry},
  year={2008},
  volume={72},
  pages={1869 - 1876}
}

• S. Kada, Masahiro Yabusaki, +2 authors Ken-ichi Yoshida
• Published 23 July 2008
• Biology, Medicine
• Bioscience, Biotechnology, and Biochemistry

Natto is a traditional Japanese food made from soybeans fermented by strains of Bacillus subtilis natto. It gives off a strong ammonia smell during secondary fermentation, and the biochemical basis for this ammonia production was investigated in this study. When natto was fermented by strain r22, ammonia production was shown to involve degradation of soybean proteins releasing amino acids, and only the glutamate contained in the natto obviously decreased, while the other amino acids increased during secondary fermentation. Strain r22 has two active glutamate dehydrogenase genes, rocG and gudB, and inactivating both genes reduced ammonia production by half, indicating that deamination of glutamate was one of the major ammonia-releasing reactions. In addition, urease encoded by ureABC was found to degrade urea during secondary fermentation. A triple mutant lacking rocG, gudB, and ureC exhibited minimal ammonia production, suggesting that the degradation of urea might be a further ammonia-releasing reaction.