Fermentation by the natto bacillus
No contamination by miscellaneous bacteria
The natto bacillus that is used to produce natto is a type of bacteria called a spore-forming bacteria. If the environment is inhospitable for the natto bacillus in terms of nutrients, temperature and so on, the bacillus has the ability to change into a spore to protect itself. Thus even among bacteria it is it known to be able to withstand hostile environments.
These characteristics of the natto bacillus are used skillfully in the production of natto.
After the soybeans are steamed, the natto bacillus is sprayed at a temperature that is high enough that other miscellaneous bacteria are unable to survive. This is done to prevent contamination by miscellaneous bacteria.
When the nutritional status and growing environment of Bacillus subtilis natto deteriorate,it forms "spores" with a hard shell-like wall around itself.
This is a picture of a 2-day culture of Bacillus natto.Most of the cells are "spores" and do not divide.
When the natto bacillus is in an environment where it can reproduce aptly, the "spores" break off.Then the trophoblast emerges.The photo captures this state.Thereafter, the trophoblast repeats division and reproduces.
This photo shows a trophoblast germinating from a "spore" in its early stages of proliferation.This is a series of "trophoblasts".Although it appears to be a single cell, it is divided into individual cells at the hollows.
This is the life cycle of Bacillus natto.