Lactobacillus reuteri are Gram-positive, rod-shaped, and anaerobic. These heterofermentatic lactic acid bacterium naturally inhabit the gut of a wide range of organisms, including humans, pigs, chickens and mice.
They can also be isolated from human breast milk.
Lactobacillus reuteri is a naturally occurring component of the animal stomach and intestine microflora
L. reuteri can produce antimicrobial molecules, such as organic acids, ethanol, and reuterin. Due to its antimicrobial activity, L. reuteri is able to inhibit the colonization of pathogenic microbes and remodel the commensal microbiota composition in the host.