LACTOBACILLUS CASEI: CHARACTERISTICS, MORPHOLOGY, BENEFITS - BIOLOGY - 2025

Lactobacillus casei is a species of bacteria that is part of the group called lactic bacteria. It was discovered by Eli Metchnikoff in 1900, who described the role of this microorganism in intestinal digestion, which opened the way for this bacterium to be considered a probiotic. That is, it is capable of exerting health benefits beyond the inherent basic nutrition.

Lactobacillus casei belongs to the group of lactic bacteria, as it is useful in the fermentation of products that contain milk, such as yogurt, kefir, zeer wash and a variety of cheeses such as Parmesan and Manchego, among others.

Hence it comes that in 1919 it was designated the name "casei", whose nomenclature is mainly related to the word cheese, that is, to the Latin word "caseus", which means cheese, and also with casein, which is the milk's main protein.

With the techniques of molecular biology it has been possible to elucidate that this microorganism is really a group of species, which can even be subdivided into sub-species.

These species, although genetically similar, have dissimilar characteristics. For example, there is variation in the ability to ferment carbohydrates and in optimal temperature growth.

Lactobacillus casei can be used alone or in association with other bacteria of the same group, in order to provide different organoleptic properties to the foods in which they are included.

characteristics

Lactobacillus casei inhabits the oral and intestinal mucosa of humans. It is also widely distributed in the environment, in fermented vegetables, meat and milk.

They are generally heterofermentative, which means that they not only produce lactic acid, but also C0 ₂, small amounts of ethanol and other aromatic substances.

In relation to the optimum temperature of growth is at 37 ° C, therefore they are mesophiles, although some subspecies can resist high temperatures for a certain time.

They are considered aerotolerant anaerobes, that is, they grow perfectly under anaerobic conditions (without oxygen), but they can grow in the presence of it. In the same way, they will obtain ATP through the fermentation of carbohydrates.

Its ability to resist oxygen will depend on being able to eliminate or degrade the two highly toxic products derived from the use of oxygen, such as hydrogen peroxide and superoxide ion. This is possible with the production of enzymes such as catalase and superoxide dismutase.

They resist acids and bile salts, being able to live in a range from pH 3 to pH7. These characteristics are necessary to be able to inhabit the intestine. Something important is that to exert their probiotic action in the intestine they must be in sufficient and viable quantities to achieve the desired benefits.

Among the main biochemical characteristics of some of the L. casei subspecies we have:

Lactobacillus casei sub-esp casei

It grows at 10-40ºC and ferments Ribose, Sucrose and D-turanose.

Lactobacillus casei sub-esp paracasei

It grows at 10-40ºC and ferments a great variety of carbohydrates.

Lactobacillus casei sub-esp tolerans

Optimal growth at 10-37ºC, but it is able to resist temperatures of 70ºC for 40 min. Ferment very little carbohydrates.

Lactobacillus casei sub-esp D-Rhamnosus

It grows at 15-45ºC and ferments rhamnosa

Members of this group lack porphyrins and cytochromes, do not perform oxidative phosphorylation, and the energy they require is obtained by phosphorylation at the substrate level.

Most lactic acid bacteria can obtain energy only from the metabolism of carbohydrates and related compounds, for this reason their habitat must contain them.

The biosynthetic capacity of Lactobacillus casei is very limited. Their nutritional requirements are complex, because to grow they need the presence of vitamins, purines and pyrimidines.

They also require lipoic acid for their growth, as they use it to form Acetyl Coenzyme A from pyruvate.

On very rare occasions, L. casei has been implicated as a causative agent of any disease.

Very few cases have been reported where it is attributed to have caused endocarditis, but whose source has never been food.

Taxonomy

Domain: Bacteria

Phylum: Firmicutes

Class: Bacilli

Order: Lactobacillales

Family: Lactobacillaceae

Genus: Lactobacillus

Species: casei.

Morphology

Lactobacillus casei are characterized by being Gram positive rods, immobile and do not form spores.

They are smaller than other species, such as L. bulgarícus, L. acidophilus and L. helveticus, although some authors describe them as bacilli of great variability in shape, size and grouping with a great tendency to form chains.

Health benefits

Lactobacillus casei provides a variety of benefits that are discussed below:

Restoration of the intestinal microbiota in diarrheal processes

Its presence in the intestine is healthy, since in healthy individuals it is capable of maintaining the balance of the intestinal microbiota.

In patients with diarrhea caused by prolonged antibiotic therapies or gastrointestinal infections by enteropathogenic bacteria, they are capable of restoring the intestinal microbiota and fighting the infection.

Especially it has been seen to be very useful in infections by Clostridium difficile in the intestine and by rotavirus.

Prevents the appearance of colon cancer

It is also useful for the prevention of colon cancer by reducing enzymes that are directly related to this type of cancer.

The enzymes involved are glucuronidase, nitroreductase, and glycocholic acidhydrolase. These enzymes in high concentrations increase the rate of conversion of procarcinogenic to carcinogenic cells in the intestine, increasing the risk of colon cancer.

Helps patients with lactose intolerance

The consumption of yogurt and milk fermented with L. casei is recommended for people who do not have lactase in their body, since in these foods the lactose is more digested and it is easier for them to tolerate it.

Stimulation and strengthening of the immune system

It increases innate immune response promoting the immunoenhancing capacity of nonspecific immune system cells, including macrophages.

Increases the acquired immune response by increasing B lymphocytes, production of tumor necrosis factor, interferon gamma and interleukin 12. Also regulatory cytokines (IL-4, IL-10).

It also improves both systemic and mucosal immunity. In the latter, it increases secretory immunoglobulins A.

This is how L. casei maintains homeostasis in the mucosa, stimulating the immune system in various permanent and effective surveillance mechanisms. One of these mechanisms is the stimulation of the secretory immune system through IgA antibodies.

Likewise, L. casei, together with the rest of the protective microbiota, prevent the invasion and colonization of pathogenic microorganisms by competing for receptors and / or metabolic substrates.

Reduction of plasma cholesterol

The mechanism is not known, but it has been shown that people who consume products containing L. casei do not increase their plasma cholesterol levels.

Therefore, it is beneficial to prevent cardiovascular diseases such as atherosclerosis.

Adjuvant in the treatment against

The consumption of foods fermented with L. casei improves the tolerance of the strong combined treatment of antibiotics in this pathology, since it helps the intestinal microbiota not lose its balance and thus avoid diarrhea caused by antibiotic therapies.

References

1. Galdeano CM, Perdigón G. The Probiotic Bacterium Lactobacillus casei Induces Activation of the Gut Mucosal Immune System through Innate Immunity. Clinical and Vaccine Immunology. 2006; 13 (2): 219-226.
2. Tursi A, Brandimarte G, Giorgetti GM, Modeo ME. Effect of Lactobacillus casei supplementation on the effectiveness and tolerability of a new second-line 10-day quadruple therapy after failure of a first attempt to cure Helicobacter pylori infection. Med Sci Monit. 2004; 10 (12): 662-666.
3. Figueroa-González, I. et al. Antimicrobial effect of Lactobacillus casei strain Shirota co-cultivated with Escherichia coli Rev. Mex. Ing. Quím 2010, 9 (1): 11-16.
4. Wikipedia contributors. Lactobacillus casei. Wikipedia, The Free Encyclopedia. September 6, 2018, 04:03 UTC. Available at: en.wikipedia.org
5. Alonso F and Isay Saad. Bacteria of the Lactobacillus casei group: characterization, viability as probiotics in food and their importance for human health. Arch Latinoam de Nutr 2007; 57 (4): 1-9