Natto is a traditional Japanese fermented food made by fermenting cooked soybeans with Bacillus subtilis var. natto. The short, warm fermentation produces the characteristic sticky, stringy texture from polyglutamic acid, along with a pungent aroma and strong umami flavour that devotees prize. Nutritionally it is rich in protein, vitamin K2 as menaquinones, and the enzyme nattokinase, and it contains probiotic spores. Commercial production demands precise control of steaming, inoculation, temperature, and time, plus hygienic handling, since the high-moisture, protein-rich substrate could otherwise support pathogens alongside the desired culture.