10 facts about the microbiome worth knowing.

Microorganisms were mainly associated with disease until the early 1990s, when scientists took a closer look at the microbes living in our bodies and on our skin. Currently, the microbiome is increasingly called a separate organ due to the role that microorganisms play in human functioning. And it's the largest organ! All the microbes in an adult's body can weigh about 2-3 kg ¹ . Their main habitat is the intestines, but they inhabit the entire surface of our body.

Previously, these tenants of the human body were called "flora", but now this term is being abandoned, because "flora" means plants, while microorganisms are living organisms. The terms "microbiome" or "microbiota" are more appropriate . Microbiota means all microorganisms (bacteria, fungi, viruses and archaea) that inhabit the human body, and the microbiome is a collection of their genes ² . Find out what these clever little guys are capable of.

1. Bacteria are what make us, as humans, so different from each other.

Each of us shares 99.99% of our genes with other people. However, the composition of the microbiota is 80-90% different ³ . That's why it's so hard for scientists to define what a "normal microbiome" is.

2. Without bacteria, we would not be able to digest food.

Intestinal microbes produce enzymes that digest complex carbohydrates and extract nutrients from what we eat ⁴ .

3. Different parts of our body are inhabited by different types of bacteria.

Some types of them, e.g. on the thumbs, never spread to neighboring fingers because they simply cannot survive in other conditions ⁵ . In this respect, our body is similar to a map of the world's population. Different countries (i.e. areas of the body) are inhabited by different nationalities (types of bacteria).

4. The diversity of bacteria is more important than the mere presence of specific species or strains.

In this respect, residents of highly developed countries fare much worse than traditional communities from poorer parts of the world. Thanks to contact with nature and an abundance of plants in their diet, traditional communities have a richer microbiome ⁶ .

5. The composition of our microbiota is most influenced by diet and lifestyle.

The composition of the microbiota changes depending on age, gender, previous diseases and treatments, as well as place of residence. However, the most reliable tool we can use to influence our bacteria is diet . Microorganisms love fiber, so the best thing we can serve them is a variety of origin foods. plant ⁷ .

6. The composition of the intestinal microbiota is related to obesity.

Scientists detect significantly fewer bacterial species in overweight people ⁸ . Studies involving mice genetically predisposed to obesity found that transplanting microbiota from lean rodents caused overweight rodents to lose weight ⁹ .

7. Microbiota guards our immunity.

Therefore, it is inextricably linked to autoimmune diseases. Scientists even claim that it is the inheritance of bacteria in the family that predisposes to these diseases, not DNA ¹⁰ .

8. Bacteria help us feel happy.

As much as 90% of the "happiness hormone" serotonin is produced in the intestines. Bacteria support this process because they themselves need serotonin to grow ¹¹ . And at the same time, humans can also benefit from its benefits.

9. The human microbiome begins to form already in fetal life.

Although it was previously believed that a baby's digestive system was sterile at birth. Recent scientific reports indicate that the fetus's intestines contain bacteria passed on by the mother ¹² . Therefore, an expectant mother must take care of her microbiome before pregnancy to give her baby the best start.

10. Most gut bacteria cannot be grown in the laboratory.

This is because they are anaerobes. There is no way to grow them in the laboratory and observe the differences in vitro. Therefore, they are tested using PCR genetic tests. Bacteria may look the same but perform different functions in the body. Scientists therefore look for differences between individual strains in a specific fragment of their DNA ¹³ .

Bibliography:

1.  “Fast Facts About The Human Microbiome”, Center for Ecogenetics and Environmental Health. Washington.edu, accessed December 20, 2021.
2. “Microbiome Vs Microbiota”, fiosgenomics.com, accessed December 20, 2021.
3. Ursell LK, Metcalf JL, Parfrey LW, Knight R., “Defining the human microbiome.” Nutr Rev. 2012
4. Kaoutari A., Armougom F., Gordon J. et al., “The abundance and variety of carbohydrate-active enzymes in the human gut microbiota.” Nat Rev Microbiol 2013
5. “Gut Check: Exploring Your Microbiome,” University of Colorado Boulder University of California San Diego. Coursera.org, accessed December 20, 2021.
6. Obregon-Tito A., Tito R., Metcalf J. et al., “Subsistence strategies in traditional societies distinguish gut microbiomes.” Nat Commun 2015
7. “Does a plant-based diet improve gut health? An interview with Hana Kahleova”, Gut Microbiota for Health, June 17, 2020.
8. “Fast Facts About The Human Microbiome”, op. cit.
9. “Gut Check: Exploring Your Microbiome”, op. cit.
10.  “Fast Facts About The Human Microbiome”, op. cit.
11.  Satyanarayana M., “Serotonin helps gut microbes thrive,” Chemical and Engineering News, September 4, 2019.
12. Lurie A. Lurie RH, “Even the fetus has gut bacteria. Findings point to potential to improve premium growth and immune system during high risk pregnancy. Science Daily, October 23, 2019
13. Shahi SK, Zarei K., Guseva NV, Mangalam AK, “Microbiota Analysis Using Two-step PCR and Next-generation 16S rRNA Gene Sequencing.” J Vis Exp. 2019