Domain Bacteria Order Lactobacillales Rank Species | Phylum Firmicutes Higher classification Lactobacillus | |
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Similar Lactobacillus, Bifidobacterium, Bacteria, Lactobacillus casei, Lactobacillus rhamnosus | ||
Microbiology lactobacillus acidophilus
Lactobacillus acidophilus (New Latin 'acid-loving milk-bacillus') is a species of gram positive bacteria in the genus Lactobacillus. L. acidophilus is a homofermentative, microaerophilic species, fermenting sugars into lactic acid, and grows readily at rather low pH values (below pH 5.0) and has an optimum growth temperature of around 37 °C (99 °F). L. acidophilus occurs naturally in the human and animal gastrointestinal tract and mouth. Some strains of L. acidophilus may be considered to have probiotic characteristics. These strains are commercially used in many dairy products, sometimes together with Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus in the production of acidophilus-type yogurt. Its genome has been sequenced.
Contents
- Microbiology lactobacillus acidophilus
- Health effects
- Uses for lactose intolerance
- Vaginal microbiota
- Side effects
- Therapeutic applications
- References
Health effects
Some strains of L. acidophilus have been studied extensively for health effects. The Mayo Clinic publishes a list of disorders for which L. acidophilus has been tested, grading the evidence for each use from strong evidence of effectiveness, through unclear, down to strong evidence of ineffectiveness. According to the list there is good (rather than strong) evidence supporting the use of L. acidophilus or yogurt enriched with it for the treatment of some vaginal infections; effectiveness for other conditions ranges from unclear to fair negative evidence.
A blend of bacterial strains including L. acidophilus NCFM decreased the incidence of pediatric diarrhea. L. acidophilus led to a significant decrease in levels of toxic amines in the blood of dialysis patients with small bowel bacterial overgrowth. At adequate daily feeding levels, L. acidophilus may facilitate lactose digestion in lactose-intolerant subjects.
The Mayo Clinic lists use of L. acidophilus for heart disease among those "based on tradition or scientific theories" that "often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven."
Uses for lactose intolerance
There are many fermented dairy products that use L. acidophilus including yogurt and some types of cheese. Sweet acidophilus milk is consumed by individuals who suffer from lactose intolerance or maldigestion, which occurs when enzymes (lactase) cannot break down lactose (milk sugar) in the intestine. Failure to digest lactose results in discomfort, cramps and diarrhea. Some bacteria have been shown to improve lactose digestion by providing β-galactosidase, while some L. acidophilus strains have been linked to improvement in symptoms and indicators of lactose indigestion.
Vaginal microbiota
Lactobacillus acidophilus is part of the vaginal microbiota along with other species in the genus including Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus jensenii, and Lactobacillus iners. In lab experiments, L. acidophilus seemed to decrease Candida albicans’ ability to adhere to vaginal epithelial cells; however, L. acidophilus’ role in preventing yeast infections is unclear because this species of Lactobacilli has also been found not to have a very strong ability to adhere to (and thereby colonize) the vaginal cells.
Side effects
Although probiotics are generally safe, when they are used by oral administration there is a small risk of passage of viable bacteria from the gastrointestinal tract to the blood stream (bacteremia), which can cause adverse health consequences. Some people, such as those with a compromised immune system, short bowel syndrome, central venous catheters, cardiac valve disease and premature infants, may be at higher risk for adverse events. In children with lowered immune systems or who are already critically ill, consumption of probiotics may rarely cause bacteremia or fungemia, leading to sepsis, which is a potentially fatal disease. Scant complaints of mild gastrointestinal discomfort or gas have been noted.
Therapeutic applications
Lactobacillus acidophilus is a constituent in VSL#3. This proprietary, standardized, formulation of live bacteria may be used in combination with conventional therapies to treat ulcerative colitis.
