What is a taxonomy?
Taxonomy is known as the science for naming, grouping and classification of organisms. The taxonomy of lactic acid bacteria are divided into genus (Limosilactobacillus), species (reuteri) and strain (DSM 17938).
What has changed?
As of now many probiotic bacteria previously known as Lactobacillus have been renamed. Lactobacillus reuteri will from now on be known as Limosilactobacillus reuteri.
However, it is only the genus part, Lactobacillus, that will be changed. Species and strain names remain the same, and of course, the organisms themselves, including their effects and safety.
Why a change?
The first Lactobacillus species was named in 1901. Initially, Lactobacillus and other genera of bacteria were identified by their shape, colour or the chemical reactions they performed. During the major part of the 20th century discovery of new species was manageable and as of 1980 only 36 species of Lactobacillus were identified.
However, improved tools, such as DNA and genome sequencing, have enabled scientists to discover many new types of bacteria. In March 2020 the genus Lactobacillus suddenly included 261 species.
According to scientists these species were extremely diverse at phenotypic, ecological and genotypic levels which became a problem. Scientists concluded that the species historically grouped under Lactobacillus were too different from each other. A group of experts was set out to modify the whole Lactobacillus genus and create a more accurate and organised group.
Basically the Lactobacillus genus became too crowded. The genus members became hard to identify with the different appearance and properties of each member. The scientist concluded that a taxonomy change was necessary and new genus names was suggested.
The scientists finally decided to limit the Lactobacillus genus to only 35 species. The other species within the genus was put into 23 new genera with new genus names.
Luckily the new and old names are quite similar and the short form of each name will remain the same (L. reuteri is still L. reuteri).
Limosilactobacillus - The slimy bacteria
The meaning of Limosus (Latin), 'slimy', does not perhaps sound that nice. But the 'slime' produced by all species within the Limosilactobacillus genus is a substance known as exopolysaccharides (EPS). The production of EPS comes from sucrose and supports biofilm formation in the digestive tract. Some probiotic health benefits, such as effects on immune system and inhibition of pathogenic bacteria, has been connected to EPS.
So far 17 species have been identified within the genus of Limosilactobacillus, BioGaia's L. reuteri being one of the strains.
Are there consequenses?
What does this mean for people using dietary supplement with probiotics and doctors prescribing them? In most cases this will not have any impact.
For consumers the change will be noticed on the package label or in the product information. The content of the probiotic is exactly the same as before. A full transition from old to new taxonomy will take time, probably years.
Hopefully this will contribute to the understanding of properties of certain probiotic strains belonging to a more specific genus.
For information about specific probiotics you should search for clinical trials using both the former and new strain name.
The article describing the new taxonomy (published in IJSEM) includes an overview of the new strain names. There is also a tool that allows you to check the conversion from ‘old’ to ‘new’ or vice versa