The law of Symbiosis -All the important things were taught by the intestinal bacteria.chapter1-1

Tomotari Mitsuoka
Professor Emeritus, University of Tokyo
RIKEN Emeritus Researcher

Chapter 1　What the intestinal bacteria teach us.

"Microcosm" called intestinal flora

As you cultivate the intestinal bacteria, you can see that the same species gather to form one colony (village).
These various colonies are densely packed in the intestine, and the whole looks like an ecosystem, so to speak, a microcosm.
Recently, the term "intestinal flora" has become well known, but just as flora means a flower field, it refers to the ecosystem of bacteria in the intestine, the intestinal environment itself.
Imagine a flower field of bacteria that spreads in your intestines.
In our intestines, small invisible creatures repeatedly increase and decrease to create their own homes, and they are still alive. Not only is what we eat absorbed into our bodies and becomes energy, but some of it becomes food for bacteria and supports their lives.
In other words, what kind of bacteria propagate and how much depends on what we eat.
Bifidobacteria, in particular, holds the casting board that harmonizes the intestinal flora and supports the health of the host human. Fermentation can be thought of as a state of such harmony.
If you think of the inside of the intestine as an ecosystem, that is, a microcosm, you will be asked whether you can live a life that matches the will of the universe.
You can tell it by listening to the voice of the intestines, which is simple and clear. To put it more simply, the answer always comes out as a stool.
Just as stool means "news" in Japanese, it can be said to be the message that the body sends. If you look at the daily news, you can immediately tell what kind of life you are living, whether you are living comfortably and happily, or if something is stuck and you feel uncomfortable.

Research on intestinal bacteria began in this way

I've talked a lot about the relationship between these intestinal bacteria and meal. No, looking back, I think most of the stories were like that, but the important thing is the way of life.
Behind the way of eating, each person's way of life is spreading. Behind the way of life, there will be a way of thinking and consciousness that supports it.
By studying intestinal bacteria, I came to feel the connection between the small universe of the intestine and the large universe of the real world.
The ecosystem in the microscope also overlaps with the activities of human society. Everything is connected and never unrelated.
How should a person live? What do they want and what should they live for? That's what I've always held in my heart and asked since I was a boy, long before I became a scholar. Even after becoming a scholar, I think that what I have cherished most is the way of thinking and philosophy to live better.

I started working on intestinal bacteria research after I entered graduate school in 1953, but I wasn't interested in this field from the beginning.
When I was a teenager, I met some of the best teachers and was fortunate to receive the scent that would determine the future.
I think the reason why I became a researcher was that I took a class from one of them, Professor Fumio Maekawa, who was a botanist. It was around the age of 15 to 16 when I entered high school.
At that time, Professor Maekawa had just become an assistant professor in the Department of Plant Science, Faculty of Science, the University of Tokyo, and was assigned to Seikei Gakuen where I was as a part-time lecturer. Therefore, the class included new knowledge of botany that was being studied at the university, and each story was very exciting.
"In botany today, this classification is the norm, but from the perspective of new phylogeny, I think it's appropriate to classify it, but I won't write it in the university entrance exam answer. Please“
Until then, botany was similar to natural history, where unknown plants were collected and recorded, but Professor Maekawa was like a pioneer in new plant taxonomy based on the phylogeny of biology.
I may have been fascinated by the large-scale ideas and awakened to the fun of research.

Later, it was used to classify intestinal bacteria, but my father died early, so my major in college was veterinary medicine, which was advantageous in the future. In veterinary medicine, the bacteria that live in livestock are the subject of research, so the subject of interest naturally shifted from plants to bacteria.
I think I liked observing and classifying such creatures rather than the plants themselves and the bacteria themselves.
The fun of taxonomy lies in the fact that all things in this chaotic world are put together into one system based on their shapes and properties.
It is reckless as well as systematizing the universe, but only then can scholarship be established. It creates a foundation for sharing various knowledge with people all over the world and deepening their understanding.

How to identify the myriad of intestinal bacteria?

The study of intestinal bacteria started in this way, but at that time it was an almost untouched area, and the situation was almost empty.
What kind of bacteria live in the intestines of humans and animals and what kind of effects do they have? Because nothing was known for certain.
Bacteria are divided into cocci, bacillus, streptococci, streptobacillus, staphylococci, coryneform bacteria in the shape of Y, V, T, and spiral bacilli, etc.-according to their shape.
In classifying intestinal bacteria, in addition to these shapes, test items such as growth temperature, type of sugar to be decomposed, presence or absence of gas production, Gram stain result (positive or negative), aerobic or anaerobic, etc. I gave it to.
For example, if the cultured bacterium is anaerobic, the shape is a conical bacterium, and the Gram stain is positive, it can be identified as a bifidobacteria.
Based on these properties, when applied to the phylogenetic tree of evolution, "Actinomycetes, Actinomycetes, Bifidobacteriales, Bifidobacterium " ... You can get the scientific name. Think of it as the taxonomic "family register" to which bifidobacteria belong.
Of course, there is more than one type of bifidobacterium, so various bifidobacteria belong to this genus bifidobacterium.
With the establishment of culture technology, such bacteria have been discovered one after another, and it is now clear that 10 out of more than 30 types of bifidobacteria inhabit the human intestine.