The MOST Important Gut Bacteria – with Dr Teitelbaum; – your SV Ayurveda Newsletter Sept 18, 2026, #36, Vol 16

The

Keystone Species of the

Gut Microbiome

~ Dr Marianne Teitelbaum

The Human Genome Project which began in 1990 and was completed in 2003, with remaining gaps largely filled in by later projects, identified the roughly 20,000 genes within human. Today scientists continue to study how genes are regulated, how they interact with one another and sequence genomes from many different people to understand disease and human diversity. 

Just as important, or even more importantly, the Human Microbiome Project started in 2007. The scientists discovered something surprising: our bodies contain trillions of microorganisms — bacteria, viruses, fungi and parasites — that collectively have millions of genes, vastly outnumbering the approximately 20,000 human genes. 

Thus, the microbiome became such a major focus is because our genes alone don’t explain many diseases. Two people can have nearly identical genomes but different risks of obesity inflammatory bowel disease, allergies, or even responses to medications. And it now appears that the microbiome is one important factor in helping to explain these differences. 

Your genome is like the blueprint of a house. Your microbiome is like the people living in the house. They don’t change the blueprint, but they can dramatically affect how the house functions. 

The point I’m making here is that it is important for us to understand the workings of our gut microbiome, because unlike the genes we’ve inherited and whose traits we cannot change, we can improve the function of our gut microbiome if we understand what throws it out of balance and even more importantly, how to repair it when it does go out of balance.

I am attempting to educate the public as much as I can as I read the latest research on the gut — through my books, articles, podcasts and videos.

In today’s video I would like to discuss the Keystone Species — an integral part of the gut microbiome.

There are a group of beneficial bacteria within the gut microbiome, known as the keystone species, which while they only make up a small percentage of all the bacteria in your gut, many other microbes and even your own body, depend on what they do.

The term “keystone” comes from the study of architecture. Imagine an arch made of stones. The keystone is the stone at the very top. It doesn’t have to be the biggest stone, but it locks all the others into place. Remove it, and the arch becomes unstable or may collapse.

The gut microbiome contains roughly 500-1,000 beneficial species in a typical healthy adult, although any one person usually carries about 150-300 species. Of those only a relatively small number are thought to be true keystone species, anywhere from 1 to 25% depending on each individual person. 

While scientists don’t yet know the exact number, current estimates suggest that there are probably dozens rather than hundreds of keystone species. As microbiome research advances, scientists continue to discover additional organisms that may qualify as keystone species, so the list is still evolving. 

A microbiome with hundreds of species but missing its keystone organisms may not function well. Just like in an orchestra: the violin section may have 30 musicians, but without the conductor the orchestra loses coordination.

Keystone species are like the conductors of the microbial community. They don’t necessarily do the most of the work themselves, but they coordinate and support many of the processes that keep the gut ecosystem functioning smoothly.

Akkermansia muciniphila is one of the most intensively studied beneficial gut bacteria because it appears to play important role in maintaining health. It was first identified in 2004 and research into it is expanding rapidly:

• It maintains the gut lining — it lives in the mucus layer that coats the intestines.
• It feeds on old mucus, but in doing so it stimulates the body to produce new mucus.
• This helps keep the protective barrier between the contents of the intestine and the bloodstream healthy. 

A healthy amount off Akkermansia is associated with lower levels of inflammation — it can influence immune cells in the gut, preventing the immune system from overreacting to harmless substances. 

It helps support the “tight junctions” between intestinal cells. A stronger barrier makes it harder for bacteria and bacterial toxins to pass into the blood stream. 

People with higher levels of Akkermansia often have better insulin sensitivity, better blood sugar control, lower body fat and healthier cholesterol and triglyceride levels. 

Studies suggest it helps “educate” the immune system so it responds appropriately to threats while remaining tolerant of beneficial microbes and food proteins. 

Faecalibacterium prausnitzii, another keystone species, is one of the most important beneficial bacteria in the colon because it produces butyrate, a short-chain fatty acid that nourishes the cells lining the colon. It helps reduce inflammation and strengthens the intestinal barrier. In fact people with inflammatory bowel disease such as ulcerative colitis and Crohn’s disease usually have low levels of this bacteria.

Look at my video on YouTube on butyrate where I describe how butyrate is made and the huge role it plays in making mucus to support the growth of Akkermansia, in addition to many other things.

Bifidobacterium longum, along with other bifidobacterium species is one of the first beneficial bacteria to colonize infants. It produces vitamins and beneficial acids. It supports normal immune function and helps crowd out harmful bacteria. 

Ruminococcus brodi is considered a “primary degrader” of resistant starches. It breaks down resistant starches or starches which are resistant to digestion, into nutrients that feed many other beneficial microbes. 

There are several other keystone species as well which work together to maintain a healthy gut environment, support butyrate production, mucus production, the breakdown of fibers and sharing nutrients with other microbes. 

Many companies are trying to make specific probiotic species, but it is difficult at times because many of these species are anaerobic, which means they cannot grow in the presence of oxygen. 

But these friendly bacteria in the gut work in harmony with each other, as colonies, each helping the next to thrive in various ways. Therefore it is felt that you can increase these species naturally and have a larger effect than you can by taking an isolated supplement. 

This would include a diet rich in polyphenol foods such as cranberries, blackberries and blueberries, pomegranates, grapes, berries, and olive oil. 

It would also include prebiotic fibers, which the friendly bacteria in general and the keystone species specifically, love to eat, such as chicory root, Jerusalem artichokes, kiwi fruit, asparagus, apples, and dandelion greens. 

Also incorporate foods containing resistant starch such as rice, beans, lentils and oats. 

Researchers often describe keystone microbes as ecosystem engineers. They:

—decide which microbes can survive.

— produce nutrients other microbes require.

— remove waste products.

— help regulate the acidity or pH of the gut.

— they influence oxygen levels.

— they affect the immune system.

— the help maintain the intestinal barrier.

They are constantly “managing” the ecosystem.

Even though they make up such a small percentage of the microbiome, if they disappear, many more abundant species can also decline because they depend on them for their survival. 

Researchers are very interested in studying the keystone species because a microbiome with hundreds of species but missing its keystone organisms may not function well.

I hope you have learned a little more about your gut microbiome from this video! Learning the various facts about this important ecosystem, will contribute to your overall good health. 

There is a reason Hippocrates, the father of modern medicine, and the ancient seers of Ayurveda both stated that, “All diseases begin in the gut.” Therefore, the starting point for treating any disease must be with the gut microbiome. 

Thank you,

Dr. Marianne Teitelbaum

www.drmteitelbaum.com

Cinnaminson, New Jersey

856-786-3330

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