[5][6] Lactobacillus forms biofilms in the vaginal and gut microbiota,[7] allowing them to persist in harsh environmental conditions and maintain ample populations.

[9] Lactobacilli are among the most common probiotic found in food such as yogurt, and the bacteria are diverse in their application in maintaining human well-being, by helping to treat diarrhea, vaginal infections, and skin disorders such as eczema.

Homofermentative, vancomycin resistant organisms with a nomadic lifestyle that ferment a wide range of carbohydrates; most species metabolise phenolic acids by esterase, decarboxylase and reductase activities.

Heterofermentative, thermophilic, vancomycin resistant with two exceptions, Limosilactobacillus species are vertebrate host adapted and generally form exopolysaccharides from sucrose to support biofilm formation in the upper intestine of animals.

Heterofermentative, vancomycin resistant, grow in the pH range of 3–5; fermenting disaccharides and sugar alcohols but few hexoses and no pentoses.

[23] Most, but not all, healthy women have vaginal floras dominated by one of four species of Lactobacillus: L. iners, L. crispatus, L. gasseri, and L. jensenii.

[24] Lactobacilli are also proposed to produce hydrogen peroxide, which inhibits the growth and virulence of the fungal pathogen Candida albicans in vitro,[25][26] though this is arguably not the main mechanism in vivo.

[28] On the other hand, following antibiotic therapy, certain Candida species can suppress the regrowth of lactobacilli at body sites where they cohabitate, such as in the gastrointestinal tract.

Lactobacilli administered in combination with other probiotics provides benefits in cases of irritable bowel syndrome (IBS), although the extent of efficacy is still uncertain.

[31] The probiotics help treat IBS by re-establishing homeostasis when the gut microbiota experiences unusually high levels of opportunistic bacteria.

[32] Helicobacter pylori is linked to cancer, and antibiotic resistance impedes the success of current antibiotic-based eradication treatments.

[32] In addition, lactobacilli with other probiotic[33] organisms in ripened milk and yogurt aid development of immunity in the intestine mucus in humans by raising the number of immunoglobulin A (IgA (+)) antiodies.

Gastroesophageal reflux disease (GERD) is a common condition associated with bile acid-induced oxidative stress and accumulation of reactive oxygen species (ROS) in esophageal tissues that cause inflammation and DNA damage.

[34] In an experimental model of GERD, Lactobacillus species (L. acidophilus, L. plantarum, and L. fermentum) facilitated the repair of DNA damage caused by bile-induced ROS.

[34] For patients with GERD, there is significant interest in the anti-inflammatory effect of lactobacilli that may help prevent progression to Barrett’s esophagus and esophageal adenocarcinoma.

[34] Given the known microbial associations, lactobacilli are currently available as probiotics to help control urogenital and vaginal infections, such as bacterial vaginosis (BV).

The issue is, however, complex, as recent studies show probiotics can allow beneficial lactobacilli to populate sites on teeth, preventing streptococcal pathogens from taking hold and inducing dental decay.

The antibacterial and antifungal activity of lactobacilli relies on production of bacteriocins and low molecular weight compounds that inhibit these microorganisms.

[43] The bacteria metabolize sugars into lactic acid, which lowers the pH of their environment and creates the signature sourness associated with yogurt, sauerkraut, etc.

The resulting mix of salt and lactic acid is a hostile environment for other microbes, such as fungi, and the vegetables are thus preserved, remaining edible for long periods.

[45] Scientist Elie Metchnikoff won a Nobel prize in 1908 for his work on LAB, the connection to food, and possible usage as a probiotic.