Lactobacillus reuteri

Lactobacillus reuteri is a Gram-positive bacterium that naturally inhabits the gut of mammals and birds. First described in the early 1980s, some strains of L. reuteri are used as probiotics. At the turn of the 20th century, L. reuteri was recorded in scientific classifications of lactic acid bacteria, though at this time it was mistakenly grouped as a member of Lactobacillus fermentum. In the 1960s, further work by microbiologist Gerhard Reuter – for whom the species eventually was named – began to distinguish L. reuteri from L. fermentum. Reuter reclassified the species as 'Lactobacillus fermentum biotype II'. L. reuteri was eventually identified as a distinct species in 1980 by Kandler et al. This group found significant differences between L. reuteri and other biotypes of L. fermentum, and thus proposed it be given formal species identity. L. reuteri was then recognized as a separate species within Lactobacillus. In the early 1980s scientists began to find L. reuteri in many natural environments. It has been isolated from many foods, especially meat and milk. Interest in L. reuteri began to increase when scientists found it colonizing the intestines of healthy animals. Reuter first isolated L. reuteri from human fecal and intestinal samples in the 1960s. The same experiments – attempting to isolate L. reuteri from feces and intestine of healthy animals – were done on nonhuman species, demonstrating that L. reuteri seems to be present throughout the animal kingdom. For example, L. reuteri was discovered to be present naturally in the intestines of healthy sheep, chickens, pigs and rodents. Furthermore, a study searching for 18 major species in the gut microbiota, including L. acidophilus, in a variety of animals found that L. reuteri was the only species to constitute a 'major component' of the Lactobacillus species present in the gut of each of the tested host animals. It is one of the most ubiquitous members of the mammalian gut microbiota. In a related discovery, each host seems to have a host-specific strain of L. reuteri, e.g. a rat strain for rats, a pig strain for pigs, etc. The universality of L. reuteri, in conjunction with this evolved host-specificity, led scientists to make inferences about its importance in promoting the health of the host organism. L. reuteri is marketed by Swedish company BioGaia AB, which owns patents on several strains as well as other patents regarding commercial usage of L. reuteri.