Probiotic Strain Names: Genus, Species, Strain Codes and the 2020 Lactobacillus Renaming
How probiotic names work (genus, species, strain code), what changed when Lactobacillus was split into 25 genera in 2020, and how to match an old label name to a new one.
Content last updated . This page has not been medically reviewed.
How a probiotic name is built
ISAPP says a label should show the genus, species and strain designation of each strain. [3]| Part | Example | What it tells you |
|---|---|---|
| Genus | Lactobacillus (older) or Lacticaseibacillus (newer) | The broad group |
| Species | rhamnosus | A kind within the group |
| Strain | GG | A specific lineage; studies are tied to it |
A systematic review of 228 trials found evidence of strain specificity and disease specificity for probiotic efficacy. [4] It also found that some Lactobacillus strains showed efficacy for preventing adult antibiotic-associated diarrhea while other Lactobacillus strains did not. [4] That is why a species name alone is not enough.
What changed in 2020
The taxonomic note by Zheng and colleagues said the genus Lactobacillus comprised 261 species at March 2020 and proposed reclassification into 25 genera. [1] The authors said the general word "lactobacilli" remains useful for all organisms classified as Lactobacillaceae until 2020. [1] ISAPP adds that all the new genera begin with "L", so the short form "L." and abbreviations such as L. rhamnosus remain unchanged. [2]Old and new names for some well-known species
ISAPP published this list of current and new names.| Older name | Newer name | Source |
|---|---|---|
| Lactobacillus casei | Lacticaseibacillus casei | [2] |
| Lactobacillus paracasei | Lacticaseibacillus paracasei | [2] |
| Lactobacillus rhamnosus | Lacticaseibacillus rhamnosus | [2] |
| Lactobacillus plantarum | Lactiplantibacillus plantarum | [2] |
| Lactobacillus brevis | Levilactobacillus brevis | [2] |
| Lactobacillus salivarius | Ligilactobacillus salivarius | [2] |
| Lactobacillus fermentum | Limosilactobacillus fermentum | [2] |
| Lactobacillus reuteri | Limosilactobacillus reuteri | [2] |
| L. acidophilus, L. delbrueckii subsp. bulgaricus, L. crispatus, L. gasseri, L. johnsonii, L. helveticus | Unchanged | [2] |
Bifidobacterium is not part of this change. When ISAPP's page was last updated (June 2025), it said bacteria in the group Bifidobacterium had not changed, though it expected changes. [2]
Why old and new names both appear
Recent papers mix the systems. A 2026 IBS review lists "Lactiplantibacillus plantarum 299v (DSM 9843)" next to "Lactobacillus rhamnosus GG" and "Bifidobacterium longum (formerly Bifidobacterium infantis) 35624". [5] A 2026 colic review uses both "Limosilactobacillus reuteri DSM 17938" and "L. reuteri DSM 17938". [6] A 2026 storage study found inconsistencies in taxonomic nomenclature across all the products it examined. [7]Tip: when a label name and a paper name differ, compare the strain code and any culture-collection number (such as DSM 17938). If they do not match, you cannot assume the same strain.
Related pages
Probiotic strains and labels, Lactobacillus and Bifidobacterium probiotics and Strain specificity.Frequently asked questions
What is Lactobacillus renamed to?
It depends on the species. For example, L. rhamnosus is now Lacticaseibacillus rhamnosus and L. reuteri is now Limosilactobacillus reuteri. [2] Some, such as L. acidophilus, are unchanged. [2]
Is Lactobacillus rhamnosus GG the same as Lacticaseibacillus rhamnosus GG?
Per ISAPP's list, the species name rhamnosus carries over to the new genus Lacticaseibacillus, and the strain code is the part that identifies the strain. [2]
Why did scientists rename it?
The genus had 261 species at March 2020, and the authors reclassified it using whole-genome data into 25 genera. [1]
Do I need to worry if my label uses the old name?
The old name alone is not a problem; ISAPP's page shows the species names carried over. What matters is whether the strain code is listed. [2] Ask a pharmacist if unsure about a product.
Did Bifidobacterium also change names?
ISAPP's page (updated June 2025) said it had not changed, though changes were expected. [2]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Limits and uncertainty
- Taxonomy is a naming system, not a safety or benefit rating. A new name tells you nothing about whether a strain works. NCCIH says different probiotics may have different effects. [8]
- Labels may lag behind the science, and the sources we read do not describe any legal rule about when a maker must switch to the new names, so follow the strain code.
Safety and who should ask first
References
- Zheng J et al. A taxonomic note on the genus Lactobacillus: Description of 23 novel genera, emended description of the genus Lactobacillus Beijerinck 1901, and union of Lactobacillaceae and Leuconostocaceae. Int J Syst Evol Microbiol 2020. PMID 32293557. Read 2026-10-22.
- Sanders ME, Lebeer S. New names for important probiotic Lactobacillus species. ISAPP, 2020, updated 21 June 2025. Read 2026-10-22.
- Sanders ME. Decoding a Probiotic Product Label. International Scientific Association for Probiotics and Prebiotics (ISAPP), 2022, updated 21 June 2025. Read 2026-10-22.
- McFarland LV, Evans CT, Goldstein EJC. Strain-Specificity and Disease-Specificity of Probiotic Efficacy: A Systematic Review and Meta-Analysis. Front Med 2018. PMID 29868585. Read 2026-10-22.
- Maslennikov R et al. Strain-Specific Systematic Review with Meta-Analysis of Probiotics Efficacy in the Treatment of Irritable Bowel Syndrome. J Clin Med 2026. PMID 41682832. Read 2026-10-22.
- Carvajal Mendez K et al. Efficacy and Safety of Limosilactobacillus reuteri DSM 17938 in Infantile Colic: A Narrative Review From Pathogenesis to Clinical Practice. Cureus 2026. PMID 42211616. Read 2026-10-22.
- Brousilova T et al. Storage temperature as a determinant of probiotic long-term stability in commercial dietary supplements. Front Nutr 2026. PMID 42824401. Read 2026-10-22.
- NCCIH (US National Center for Complementary and Integrative Health). Probiotics: Usefulness and Safety. Page shows Last Updated August 2019. Read 2026-10-22.
- NHS (UK). Probiotics. Page last reviewed 24 November 2022. Read 2026-10-22.