ABSTRACT
A Gram-positive rod-shaped Bacillus strain was isolated from natto and named Bacillus natto (Sawamura 1906). Later, B. natto was included in Bacillus subtilis in Bergey’s Manual of Determinative Bacteriology, 8th edition, because of the biochemical and bacteriological similarities between them (Gibson and Gordon 1974). DNA-DNA hybridization and phylogenic analyses of Bacillus strains strongly supported the fact that Bacillus strains isolated from natto or natto starters were B. subtilis (Seki et al. 1975, Tamang et al. 2002, Kubo et al. 2011). Industrial strains of B. subtilis used for producing natto are, however, often called B. subtilis (natto) to distinguish
Contents 13.1 Introduction................................................................................................................. 433 13.2 Nutritional Aspects of Natto .........................................................................................435 13.3 Functional Aspects of Natto ......................................................................................... 437
13.3.1 Nattokinase .................................................................................................... 437 13.3.2 Antibiotic Activity .......................................................................................... 439 13.3.3 Probiotics ....................................................................................................... 441 13.3.4 Immunomodulating Activity ......................................................................... 442 13.3.5 Antitumor Activity ......................................................................................... 443 13.3.6 Vitamin K ...................................................................................................... 443 13.3.7 Isoavones ...................................................................................................... 445 13.3.8 Angiotensin I-Converting Enzyme Inhibitor .................................................. 446 13.3.9 Saponins ......................................................................................................... 446 13.3.10 Polyamines ..................................................................................................... 447
13.4 Conclusion ................................................................................................................... 447 References ............................................................................................................................... 447
them from the typical strains of B. subtilis, which cannot produce natto. B. subtilis (natto) is also distinguishable from B. subtilis by its requirement for biotin (Kida et al. 1956). Interestingly, the type strain of B. subtilis has no plasmids or insertion sequences, as found in B. subtilis (natto) strains (Tanaka and Koshikawa 1977, Hara et al. 1981, Nagai et al. 2000, Kimura and Itoh 2007). Other important dierences are: natto is characterized by an ammonia odor, short-chain fatty acids (Ikeda and Tsuno 1984, Kanno et al. 1984), and a highly viscous polymer composed of polyγ-glutamic acid (PGA) and levan (fructose polymer) (Fujii 1963). e viscosity of natto is due to PGA and is an important determinant of the quality of natto (Figure 13.1a).
