September 13, 2024

What is a probiotic? Definition

According to scientific literature, “probiotics” are defined as “live microorganisms, which when administered in adequate amounts, confer a health benefit on the host”.

Key role of intestinal flora

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Natural probiotics are live and active yeasts or bacteria naturally present in the body. They are primarily found in the digestive system, where they form the intestinal flora – also known as the gut microbiome.

Many well-known probiotics share health effects like supporting digestive and immune health. The most well-known probiotics belong to the genera (genus) Lactobacillus spp. and Bifidobacterium spp., but there are many other less common strains as well.

Bacteria, what are we talking about?

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The order of classification for bacteria, from the most general to the most specific level, is as follows: family, genus, species and strain. Here is an explanation of each level:

Family: this is a group of genera that share common characteristics. For example, the family Lactobacillaceae includes several different genera.
Genus: this is a group of species that are closely related. For example, Lactobacillus is a genus that includes several species.
Species: this is a group of strains that share specific genetic and phenotypic characteristics. For example, Lactobacillus acidophilus is a species within the genus Lactobacillus.
Strain: this is a population of bacteria within a species that has distinct characteristics. For example, Lactobacillus acidophilus BIO6307 is a specific strain of the species Lactobacillus acidophilus.

Focus on Lactobacillus spp.’s taxonomy

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A consensus has developed among scientific experts that, given the genetic composition of these bacteria, the current Lactobacillus genus was too diverse and did not conform to naming conventions. Additionally, it was important to divide the genus into functionally relevant groups that shared certain physiological and metabolic properties. Scientists have proposed a new classification of the Lactobacillus genus, separating them into the groups L. delbrueckii and Paralactobacillus, and adding 23 new genera based on several approaches and genetic markers.