Alkalihalobacillus clausii

Alkalihalobacillus clausii (synonym Bacillus clausii) is a rod-shaped, motile, and spore-forming bacterium that lives in the soil but is also a natural microbiota of the mammalian gastrointestinal tract. It is classified as probiotic microorganism that maintains a symbiotic relationship with the host organism.^[1] It is currently being studied in relation to respiratory infections^[2] and some gastrointestinal disorders.^[3] Bacillus clausii has been found to produce antimicrobial substances that are active against gram-positive bacteria including Staphylococcus aureus, Enterococcus faecium and Clostridioides difficile.^[1] It is sold as an Antidiarrheal under the brand name Erceflora by Sanofi.^[4]

Alkalihalobacillus clausii
Alkalihalobacillus clausii from Enterogermina on a glass slide
Scientific classification
Domain:	Bacteria
Kingdom:	Bacillati
Phylum:	Bacillota
Class:	Bacilli
Order:	Bacillales
Family:	Bacillaceae
Genus:	Alkalihalobacillus
Species:	A. clausii
Binomial name
Alkalihalobacillus clausii (Nielsen et al. 1995) Patel and Gupta 2020
Synonyms
Bacillus clausii Nielsen et al. 1995

This species has been recently transferred into the genus Alkalihalobacillus.^[5] The correct nomenclature is thus Alkalihalobacillus clausii.

The Pharmacovigilance Risk Assessment Committee (PRAC) warns about serious risks for bacteraemia and sepsis due to previous publications. PRAC stipulates marketing conditions for Bacillus clausii. Amendments to be included in the relevant sections of the Product Information (new text underlined and in bold) including

1 Bacteraemia (in immunocompromised patients)

2 In case of reduced body’s defense mechanisms and you are taking (product name) Bacillus clausii may be found in your blood.^[6]

Genomics

The genome of Alkalihalobacillus clausiiAO1125 was sequenced by researchers using Illumina technology, resulting in 25 contigs and a total length of about 4.3 megabases.^[7] The annotation of the genome revealed genes linked to gut colonization, immune system modulation, and stress resistance.^[7] Each one of these linkages further supports the probiotic role of Alkalihalobacillus clausii.^[7] The analysis also identified antimicrobial resistance (AMR) genes present with low clinical relevance and confirmed the absence of plasmids, suggesting a lowered risk of horizontal gene transfer.^[7]

Probiotic Capabilities

Alkalihalobacillus clausii has probiotic properties that can help restore gut microbiota composition altered by antibiotic treatment.^[8] A study done on mice with CFX-induced intestinal injury helped determine the mechanism A. clausii uses to do this.^[8]

Metabolic Pathways

Alkalihalobacillus clausii is an spore-forming, obligate aerobic bacterium that demonstrates versatility due to its ability to thrive in alkaline and high salt environments. A. clausii relies on many different metabolic pathways to manage variability in its environmental factors (pH, nutrient availability, salinity etc.).^[9] It is able to catabolize many different organic compounds as both a carbon and energy source, such as carbohydrates, amino acids, and organic acids.^[9]

A. clausii is classified as a chemooroganoheterotroph, utilizing Glycolysis, the Pentose Phosphate Pathway, and the Tricarboxylic Acid Cycle for carbohydrate metabolism.^[9]