10 BENEFICIAL BACTERIA FOR HUMANS AND CHARACTERISTICS - GEOGRAFÍA - 2025

Some beneficial bacteria for humans are Escherichia coli, E. coli, Bacteroides fragilices, Lactobacillus acidophilus, among others. Bacteria are ubiquitous and numerous microscopic prokaryotic organisms. We find them in different sizes and shapes.

Regarding their relationship with humans, these can bring positive, negative or neutral consequences, depending on the species and the biotic and abiotic conditions of the environment where they develop.

Source: pixabay.com

Humans have co-evolved over millions of years with microorganisms that inhabit the interior and exterior of our bodies, and that have important consequences.

Many species of bacteria have beneficial consequences for us, who act as their hosts. Among these we have resistance to virulent bacteria, digestion of nutrients, maintenance of an optimal pH, production of inhibitory substances such as antibiotics, among other benefits.

Imbalances in human microbial biota have been linked to multiple conditions, such as inflammation, sclerosis, diabetes, allergies, obesity, asthma, and even cancer and autism. Therefore, it is necessary to know the "healthy" condition of this biome, so diverse and abundant.

In this article we will discuss 10 bacteria that are beneficial to humans, describing them and highlighting their role in our well-being.

10 beneficial bacteria for humans

When we hear the term "bacteria" it is almost inevitable to associate it with a negative concept. We often instantly associate bacteria with catastrophic disease.

We are constantly trying to keep our body and environments "free of bacteria" and other microorganisms using antibacterials and detergents, in order to maintain our health in an optimal state.

However, this negative image of bacteria must be modified. While it is true that many bacteria are the causative agents of multiple pathologies, others cause immense benefits to our health, being essential.

Researchers have estimated the proportion of bacteria in our body, and they have found an overwhelming number: for each cell we have approximately 10 bacteria. This means that, quantitatively, we are more bacteria than humans.

In terms of mass, bacteria represent a negligible portion. However, in terms of genes, as an organism we have 99% bacterial genes and only 1% human genes. That is why bacteria play a very important role in different aspects of our life, including digestion, immunity and protection against diseases.

This astronomical number of bacteria makes it difficult to choose just 10 of them, but we will analyze the most famous of the scientific literature:

Escherichia coli

Escherichia coli. Source: NIAID, via Wikimedia Commons

Within biology laboratories - and also in popular knowledge, E. coli has an important place, being the best known organism on the entire planet. Not only is it useful as a model for research in molecular biology and genetics, it is also useful inside our bodies.

The presence of E. coli has been linked to the production of vitamin K and vitamin B12, both very important requirements for the mammalian host. In addition, it consumes oxygen from the intestine, maintaining an appropriate environment for its anaerobic companions. Lastly, it competitively excludes pathogenic microbes.

Eubacterium

The genus Eubacterium, like E. coli, is a symbiotic resident of our digestive tract. Contributes to the production of vitamin K, vitamin B12, folate and biotin. Other bacterial genera are also important producers of these vitamin compounds.

Bacterioids

Bacteroides comprise one of the largest lineages of bacteria that emerged during the evolutionary process. These species are characterized by being rods with anaerobic metabolism, do not form spores and respond to the Gram stain in a negative way.

These bacteria begin to form part of our microbiota from very early stages in our lives, since they are transmitted vaginally during childbirth, from mother to child.

They are found as normal inhabitants of the digestive tract. Bacteroides have the ability to ferment carbohydrates, producing a wide range of volatile fatty acids that the host can reabsorb and use for energy.

Studies have shown that animals that lack bacteria in their digestive tract require 30% more energy, since they do not have these microorganisms that contribute to generate assimilable compounds.

Colonization by Bacteroides, such as Bacteroides fragilices, has also been found to be crucial for the functioning of the immune system in mammals.

Lactobacillus

Lactobacillus acidophilus

There are more than 80 species belonging to this genus of bacteria. This genus is an important representative of the phylum Firmicutes. Specifically, the species L. acidophilus is a mutualistic inhabitant of our intestines and aids in the digestion of food.

As a result of its metabolism, it produces lactic acid and hydrogen peroxide, helping to keep the digestive tract free of pathogenic microorganisms.

In addition, they contribute to the digestion of carbohydrates that are not digestible (cellulose, peptins, etc.) and that are a key source of energy in the colon.

This bacteria is present in fermented foods, such as yogurt and is used as a probiotic. This topic will be discussed later. Consumption of these organisms has been particularly effective in patients with lactose intolerance, as it helps with the digestion of this carbohydrate.

This genus is also found in the vaginal mucosa, helping to maintain an acidic pH. Acidity helps keep pathogens away, like the Candida fungus.

Staphylococcus

Staphylococcus epidermidis

The microbiota of the skin contributes greatly to the health of its host and helps protect it against a wide range of potential infections. One way to do this is by producing bacteriocins, antimicrobial substances synthesized by the ribosomes of bacteria.

Bacteriocins are heat stable peptides that can have varied microorganism kill spectra.

The imbalance in the microbial composition of the skin has been related to the development of diseases such as psoriasis, dermatitis and acne.

Bacteria of the genus Staphylococcus are dominant inhabitants of the skin. Although some are potentially pathogenic, a specific group is part of the beneficial microbiota and helps the production of antimicrobial substances, such as S. gallinarum, S. epidermidis and S. hominis species.

Another example is S. lugdunensis. This bacterium was isolated from the nasal cavity, and led to the discovery of a new antibiotic. Thus, the study of beneficial bacteria can lead to the advancement of medicine.

Streptococcus

Bacteria of the genus Streptococccus are generally associated with diseases, however the species S. thermophilus is a beneficial microbe.

This bacterium does not have the capacity to move but to ferment. As its name implies, it is capable of withstanding high temperatures.

Regarding its metabolism, it can be aerobic or anaerobic, depending on the context. It is located in the small intestine, where it begins to ferment. Its presence in the digestive tract aids in the digestion of complex carbohydrates.

Bifidobacteria

This genus of bacteria is naturally present in our gastrointestinal tract. It seems to be important in infants, being more frequent in children who are fed through breastfeeding.

It contributes to the digestion of food, helping to break down compounds that are not easily assimilated into small, easily digestible molecules. In addition, it prevents the development of diarrhea and constipation.

One of the by-products of the metabolic activity of Bifidobacteria is the accumulation of gases in the intestine.

This bacterial genus has also shown positive in the regulation of the immune system, modulating the expression of IgG immunoglobulins.

Bacillus

The Bacillus coagulans species is usually taken in various supplements and has been found to have positive effects on pathologies of the gastrointestinal tract, such as diarrhea.

Lactococcus

This bacterial genus is found in relevant quantities in fermented dairy products. They are beneficial for the body since it seems to be used to treat allergies and inflammatory diseases.

Faecalibacterium

Like most of the bacteria described, this genus is located in the gastrointestinal tract.

The reduction of Faecalibacterium prausnitzii seems to be related to a series of pathologies, such as Bowel's disease. In addition, the bacterium has anti-inflammatory properties.

Bifidobacterium animalis

Bifidobacterium animalis is a useful strain of probiotic bacteria that naturally inhabit the human digestive tract. It is considered a probiotic because it confers a beneficial effect on humans.

It is essential for good digestion; This microorganism lives in the large intestine where it competes for food.

The intestinal lumen, stomach, colon, and intestine are colonized by the dominant microorganisms that live in the intestinal flora; therefore, when supplementing with probiotics, it is imperative to take an adequate dose that allows it to compete effectively against bacteria that can cause disease or infection.

Some probiotic bacteria colonize along the lumen walls while others, such as Bifidobacterium animalis, exert their probiotic effects as they move through the digestive system.

Bifidobacterium animalis uses a fermentation process to convert carbohydrates into chemical compounds like lactic acid and hydrogen peroxide, allowing only probiotic dominance in the entire intestinal area.

What are probiotics?

It is impossible to talk about beneficial or "friendly" bacteria without clarifying what a probiotic is, as it is a term that has gained much popularity in recent years.

According to the World Health Organization (or WHO, for its acronym in English) probiotics are microorganisms - mostly bacteria - whose presence in appropriate amounts results in a benefit for their host, being a synonym widely used to refer to good bacteria.

Although its use has grown exponentially, its use dates back several centuries, where fermented milk was used as a home remedy for the treatment of some bacterial diseases. Indeed, it was observed that its consumption brought a positive result to the patient.

Today probiotics go beyond just dairy products. They come in different presentations, from capsules, tablets, powders and others, which can be incorporated into drinks and other foods.

Why are probiotics good? These help control potential infections as the "good" bacteria compete with the "bad", and end up displacing them. They also help to restore the host's healthy microbiota after taking antibiotics that have killed it.

How do "good" bacteria become "bad"?

As we saw, there are various bacteria that coexist in mutualistic or commensal relationships with humans, without causing any harm.

However, some of these microbes have "relatives" that are known for their ability to cause devastating disease in humans. Many times we find one strain beneficial and another devastating, why is this huge difference?

The classic example is Escherichia coli, normally found in human intestines. There are some pathogenic strains of this microorganism that are the causative agents of a wide range of diseases, from simple diarrhea to hemolytic syndromes that can potentially cause the death of the patient.

In most cases, the crucial difference between a beneficial strain to another pathogenic or deadly is - surprisingly - in only a few genes found in mobile elements, such as plasmids, transposons or phages that have been integrated into the genome.

References

1. Blount ZD (2015). The unexhausted potential of E. coli. eLife, 4, e05826.
2. Cabello, RR (2007). Human microbiology and parasitology. Etiological bases of infectious and parasitic diseases. Pan American Medical Ed
3. Cullimore, DR (2010). Practical atlas for bacterial identification. CRC Press.
4. Human skin microbiota is a rich source of bacteriocin-producing staphylococci that kill human pathogens
5. Olivas, E. (2001). Basic Microbiology Laboratory Manual. Sports Training Program. UACJ.
6. Tortora, GJ, Funke, BR, & Case, CL (2007). Introduction to microbiology. Panamerican Medical Ed.
7. Troy, EB, & Kasper, DL (2010). Beneficial effects of Bacteroides fragilis polysaccharides on the immune system. Frontiers in bioscience (Landmark edition), 15, 25–34.
8. Wexler HM (2007). Bacteroides: the good, the bad, and the nitty-gritty. Clinical microbiology reviews, 20 (4), 593–621.