Central Research

The value of knowing your gut microbiota

Globally, population health is always an important issue. According to the WHO, chronic diseases kill 41 million people each year, 15 million of them in the productive age, that is, from 30 to 69 years(1). On the other hand, over the last decades, scientific advances have shown that gut microbiota (those microorganisms that reside in an ecological niche: gut, and that establishes symbiotic relationships between them and the host)(2) has a determining influence on the host’s metabolism, immune system, and inflammatory response, which determines its state of health or disease. Nevertheless, gut microbiota is a parameter that public and private health services usually do not consider indicating a treatment.

Microbiota in the human gut is found in about 10*14 bacteria and more than 95% are found in the colon, which represents between 1-3% of body weight(2). Microbiota in the colon is composed of commensals and synbiotic microorganisms (including bacteria, archaea, viruses, bacteriophages, and some fungi) (3).

This composition may vary in accord to different factors (delivering, breastfeeding, diet lifestyle, host physiology, ingested microbes that compete with resident microbiota, pharmacological treatments, geography, genetics, host inflammation, etcetera)(4). Nevertheless, there are mainly five major microbial phyla that represent about 90% of bacteria from microbiota: Bacillota, Bacteridota, Pseudomonadota, Actinomycetota, and Verrucomicrobia(5;6). And a significant fraction of these bacteria is continuously stable such as Bacteroides, Eubacterium, Faecalibacterium, Alistipes, Ruminococcus, Clostridium, Roseburia, and Blautia(6).

The study of gut microorganisms has been performance using different techniques. Nevertheless, molecular biology is the best way to determine the presence, absence, and abundance of these microorganisms because most of them are uncultured (about 75-90%) because they are anaerobic. In this context, to study them, their genetic material is isolated and studied by sequencing the 16S rRNA gene for bacteria and after sequencing, bioinformatics analyses are performed(7).

But what does the presence or absence of these microorganisms represent?

To understand their role and the importance of quantity (abundance) and variety it is necessary to know their functions and their characteristics at different levels. For example, the phyla: Bacteroidota (before called Bacteroidetes), are usually the predominant microorganisms in human gut microbiota, and they play an important role in carbohydrate metabolism, expressing enzymes such as glycosyltransferases, glycoside hydrolases, and polysaccharide lyases(7), that allows digest carbohydrates ingested on the diet.

On the other hand, the second phyla more abundant in the human gut is Bacillota (before called Firmicutes), to which belongs Bacilli, Clostridia, Erysipelotrichia, Mollicutes, Negativicutes, and Thermolithobacteria, and they play an important role in health host by degrading different kinds of fibers, breaking them out into oligosaccharides and monosaccharides that can be absorbed by human cells or using by other microbes(7;8).

On the other side, Pseudomonadota (before called Proteobacteria) the third phyla more abundant in gut microbiome, is represented by a group of microorganisms characterized by include opportunist pathogens, they are important for the digestive process too, but an increase in their abundance, may cause diseases(9;10).

Cyanobacteria are bacteria that could be ingested in food, and the presence of some genes for the biosynthesis of vitamins suggests a beneficial effect on the host. Nevertheless, there is some evidence that gut cyanobacterial abundance has a relationship between health control and diseased groups on neurodevelopment, neurodegeneration, obesity, allergy rhinitis, and other diseases (11;12).

Others two representative phyla of gut microbiota are Actinomycetota and Verrucomicrobia Actinomycetota (before called Actinobacteria) although they represent a small percentage, represents a group of commensal bacteria that is important in the development and maintenance of gut homeostasis, modulate gut permeability, immune system, and metabolism(13). While Verruomicrobia is a group of bacteria that degrades mucin and contributes to gut health and glucose homeostasis(14), the most important bacteria that belong to this phyla is Akkermansia muciniphila, which has been studied as a very promising probiotic(15).

One of the most important characteristics of gut microbiota is that it increases the host’s physiological and metabolic capacity, by promoting submucosal capillary network and immune system development. Gut microbes have about 80 families of glucose-hydrolasetype enzymes that are crucial to degrade nondigestible carbohydrates that humans ingest in food but are not able to digest. Also, they act as a barrier and protect the intestine against pathogens; they conjugate bile acids, and produce B12 and K vitamins, and short-chain fatty acids that participate in very important pathways in human metabolism(16;17;18).

Nevertheless, gut microbiota is unique for every individual, and so is gut microbiota metabolism. Recent studies determined that exists an interindividual variability given by genetic and environmental factors(5). What does it mean? Mainly, a specific treatment (diet/ supplementation) may have or not have a therapeutical effect on different hosts, it depends on host digestion and metabolism, but on the other hand, that depends also on their gut microbiota composition, digestion, and metabolism (gut metabotype). A gut metabotype is a metabolic phenotype characterized by a specific capacity to produce metabolites from a determined compound by microbes’ metabolism(19).

For example, García-Villalba et al.(20) found that some poly phenols (ellagitannins) metabolism can yield three different metabotypes depending on the individuals’ microbial profile and their metabolism will have or not an effect on human health to produce urolithins and neuroprotection. The same phenomenon was previously observed in the cardiovascular and metabolic response where the metabolism of food phytochemicals, and the production of derived metabolites will have an effect on the health host, but more studies are needed to elucidate this mechanism. For now, there are research groups that continue this work to personalize nutrition and medicine. These types of studies are being used more frequently in medicine and nutrition, and are becoming increasingly accessible to your patients, as they can provide valuable information for the diagnosis and treatment of diseases.

Blanca Elizabeth Ruiz Álvarez, M.Sc.

M.Sc. in Biotechnological Innovation specializing in Medical and Pharmaceutical Biotechnology from CIATEJ. Operations Manager of Grupo MaBiosis S.A. de C.V. since 2018. Ph.D. Candidate in Biotechnological Innovation specializing in AgriFood Technology by CIATEJ and Ph.D. candidate in Plant Biology by the Institut sur la Nutrition et les Aliments Fonctionnels (INAF), Laval University, Quebec, Canada.

References

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20. García-Villalba, R., Tomás-Barberán, F. A., Iglesias-Aguirre, C. E., Giménez-Bastida, J. A., González-Sarrías, A., Selma, M. V., & Espín, J. C. (2023). Ellagitannins, urolithins, and neuroprotection: Human evidence and the possible link to the gut microbiota. Molecular Aspects of Medicine,89, 101109. https://doi.org/10.1016/j.mam.2022.101109