Probiotic Names – Taxonomy

When we read the label on a probiotic bottle, the most important information on the label is the name(s) of the probiotic(s) in the product we are holding. Thus, we find names with Latin grammatical forms such as Latobacillus rhamnosus, Lactobacillus acidophilus or Bifidobacterium bifidum, Streptococcus thermophilus, etc, to cite some examples.

Probiotic Names - Taxonomy

The origin of these names is in the international nomenclature that is followed to name the microorganisms. This is a nomenclature called “binomial” and according to this system, the correct way to name microbial species is through two words: a first word that corresponds to the “genus” and a second – the epithet – that corresponds to the “species”.

These two words always go together, so that we refer to a particular species naming both genus and species, written in italics and with the first letter of the genus in capital letters. If in a text the species is named more than once, it is accepted that the second and other times, the name of the genus can be abbreviated to its first letter in capital letters together with a dot (e.g. Lactobacillus acidophilus or L. acidophilus)

Let’s look at some other examples.

Lactobacillus casei

If we take the microorganism Lactobacillus casei as a reference, we would be talking about the specie casei belonging to the genus Lactobacillus.

This nomenclature follows a hierarchical classification in which each level belongs to a higher level that encompasses many lower levels. Thus, according to this nomenclature, a “species” is part of a “genus” which is part of a “family” which in turn belongs to an “order” and this to a “class”. Finally, the “class” belongs to the “Phylum” and this to the “Kingdom” which in turn belongs to the “Domain”, the highest level that exists.

But as if this were not enough, this classification does not end here as we also often see that, next to the name of the microorganism, there is a code formed by letters and/or numbers: it is the specific strain of that particular microorganism.

Strain name

Strains are microorganisms of the same species but contain some genetic variant that makes them behave differently. Hence the importance of knowing exactly which strain of probiotic we want to take or buy since some of its beneficial effects are due to that particular strain and not to the species in general.

Following the previous example, we can then find probiotics containing the microorganism Lactobacillus casei DN-114 001. In this case, the final letters and numbers (DN-114 001) refer to the strain of the species Lactobacillus casei.

Therefore, the complete taxonomic classification of Lactobacillus casei DN-114 001 would be

  • Species and strain: Lactobacillus casei DN-114 001.
  • Genus (the first word of the two that make up the species): Lactobacillus.
  • Family: Lactobacillaceae.
  • Order: Lactobacillales
  • Class: Bacilli
  • Division: Firmicutes
  • Domain: Bacteria

Let’s look at some other examples:

Lactobacillus rhamnosus

In this case, we find another species of the same genus as the previous example, which is Lactobacillus. The probiotics of this species usually belong to the GG strain, so the complete taxonomic classification of Lactobacillus rhamnosus GG would be:

  • Species and strain: Lactobacillus rhamnosus GG.
  • Genus: Lactobacillus.
  • Family: Lactobacillaceae
  • Order: Lactobacillales
  • Class: Bacilli
  • Division: Firmicutes
  • Domain: Bacteria

If we compare it with the previous example, we are dealing with two different species but belonging to the same genus and therefore sharing the rest of the hierarchical classification up to the domain.

Streptococcus thermophilus

In this case, we find another species of different genus than the previous ones but that share the family Lactobacillaceae and therefore the rest of the taxonomic classification. In this case the species does not refer to any particular strain.

  • Species and strain: Streptococcus thermophilus.
  • Genus Streptococcus.
  • Family: Lactobacillaceae.
  • Order: Lactobacillales
  • Class: Bacilli
  • Division: Firmicutes
  • Domain: Bacteria

Carl Linnaeus

This form of classification was initially designed by the Swedish botanist Carl Linnaeus or Linnaeus who is considered to be of the taxonomy, that is to say the classification of living beings within biology.

This classification was defined by Linnaeus in the 18th century and is still valid today, although with the logical modifications that have been made over the years in order to improve its application to all the new species that have been discovered.

Image credit: Author Albertogilmi / CC BY 4.0

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