The role of Bifidobacterium longum in a healthy human gut

What is Bifidobacterium longum?
Definition
Bifidobacterium longum is a Gram-positive, catalase-negative, rod-shaped bacterium present in the human gastrointestinal tract and one of the 32 species that belong to the genus Bifidobacterium. It alters gut luminal metabolism through modification of the gut microbial community.

Origin
The Pasteur Institute has played a large role in the discovery and knowledge of Bifidobacterium. Bifidobacterium was first discovered in 1899 by a French pediatrician, Henry Tissier, who observed a peculiar “Y” shaped microorganism in the stool of infants having diarrhea. Tissier named these microorganisms using the Latin root “bifid” meaning divided by a deep cleft, like the letter “Y”. Later, in 1907, Nobel prize-winning immunologist, Elie Metchnikoff, suggested implanting beneficial bacteria orally would help the digestive system.

In 2002, three previously separate species of Bifidobacterium merged into one species due to DNA similarities. B. longum, B. infantis, and B. suis became B. longum as the three shared 97% DNA similarities. B. longum subspecies infantis strain 35624 has become the main microorganism related to beneficiary gut function in humans.

How many species of Bifidobacterium are there?
Bergey’s Manual of Systematic Bacteriology (1986) identified 24 different species of Bifidobacterium. Of these species, the types considered primarily human in origin are the following species: bifidum, longum, infantis, breve, adolescentis, angulatum, catenulatum, pseudocatenulatum, and dentium.

Where is Bifidobacterium longum found in the body?
Bifidobacterium longum (B. longum) is one of the many important probiotic bacteria found in the human body. It is one of the primary probiotics that is found naturally in breast-fed infants and performs a number of beneficial functions in the body.

Being a rather versatile probiotic, Bifidobacterium longum is able to survive harsh conditions in the gut. Unlike some probiotics, it isn’t affected by stomach acid, bile, pH fluctuations, or the passage through the gastrointestinal tract. Instead, it supports the gut by adhering to the lining of the intestines right through to the colon.

What foods contain Bifidobacterium longum?
BB536 is highly accessible to the human gut and highly stable in various finished products, including powdered formula, yogurt, and fermented milk with excellent stability during storage and high survivability in probiotic food until consumption.

What is the best source of Bifidobacterium longum?
Since the gut is a hypoxic environment, many foods with beneficial gut bacteria are fermented. Bifidobacterium can be found plentifully in many food types including goat dairy products, like yogurt, kefir, seaweed, and miso soup.

What is the difference between Bifidobacterium and Lactobacillus?
Lactobacilli have limited biosynthetic abilities and ferment refined sugars, generating lactic acid as the major end product (Wells, 2011), whereas Bifidobacteria are important producers of short-chain fatty acids (SCFA)

Here are the main differences between Bifidobacterium (former) and Lactobacillus (latter) respectively:
Cell Morphology
Bifidobacteria are rods, clubs or branched rods while Lactobacillus are cocci or rods

Habitat
The former is mainly found in human and animal intestines, while the latter is in general milk and dairy products, fermented foods, human and animal intestines,

Sensitivity to oxygen
Bifidobacteria is Anaerobic while Lactobacillus is Aerobic

Main metabolites
The former produces lactic acid and acetic acid, while the latter is only lactic acid

Beneficial effects of Bifidobacterium longum?
Bifidobacterium longum subsp. longum BB536 (designated as BB536) is one of the well-established probiotic strains with numerous profound health benefits in humans (Xiao, 2009). BB536 has been used as a probiotic since its discovery for half a century and many studies have been conducted to clarify its effectiveness.

Uses
Bifidobacterium longum BB536 is a multifunctional probiotic that is effective in alleviating gastrointestinal, immunological, and infectious diseases. Existing evidence implies that the multifunctional effects of BB536 are attributed to its ability to stabilize gut microbiota and improve the intestinal environment. BB536 improves immune dysfunction by driving a fine-tuned homeostatic balance within the host-microbiome interaction.

Safety
BB536 is well-evaluated for safety and has been listed on Generally Recognized as Safe (GRAS) notice inventory (GRN No. 268) in the United States Food and Drug Administration (FDA) in 2009. The GRAS status was granted based on the evidence that BB536 is a non-pathogenic, non-toxigenic, non-hemolytic, and non-antibiotic resistant probiotic bacterium that does not contain any plasmids and does not display harmful metabolic activities.

Clinical uses of Bifidobacterium longum

On digestive system
Historically, probiotics have been used in the treatment and prevention of many forms of gastrointestinal disorders, for which BB536 has long been recognized as one of the most effective probiotic strains for improvement of gastrointestinal conditions. Mounting clinical evidence has shown that the consumption of dairy products containing BB536 can improve the frequency of defecation and fecal characteristics in healthy adults with constipation.

Strains of Bifidobacterium longum are most commonly found in babies and children, usually after being transmitted from the mother during natural birth and breastfeeding. Children born via Caesarean or fed on formula may lack this important bacterium. Supplementation, in this case, is highly recommended as the colonization of B. longum can play a major role in the development of the gastrointestinal system for the rest of their life.

On the immune system
BB536 is one of the well-established probiotic strains with strong scientific evidence on their positive effects on the immune system. Supplementation of BB536 has been shown to confer health benefits by their immunomodulatory function and has been clinically evaluated for their application in the possible prevention and therapy of immune-mediated diseases.

The role of Bifidobacterium longum in a healthy human gut
In order to reap the beneficial effects of B. longum subspecies infantis strain 35624, one must first get the bacterium into the gut. Since B. longum plays such a large role in digesting oligosaccharides from breast milk, it is logical that humans are born with B. longum in their gut. Infants could possibly receive the bacterium through the umbilical cord. B. longum is also naturally found in the vagina, suggesting that the transfer of the bacterium from mother to infant could be ensured through a passage through the birth canal. Breastfeeding is another mechanism by which a mother’s gut microbiota is transferred to her child. Babies born via cesarean delivery often lack in breastfeeding while the mother takes antibiotics until her incision heals. These infants miss out on two key factors, which develop their gut microbiota.

Bifidobacterium longum subsp. longum BB536 has become one of the clinically effective documented probiotic strains that can provide consistent beneficial health effects to the human host. One of the clear advantages of BB536 is that this probiotic is a well-characterized human origin strain that is widely used for human health with a proven track record of safety and clinical efficacy.

It has become clear that the modulation of the gut microbiome is likely to be the key element of the health-promoting activity of BB536 in the human gut. BB536 acts in concert with the gut microbiota to modulate host homeostasis, improve gastrointestinal health, and alleviate allergic disorders.

B. longum is known for being resistant to gastric acid and bile. This means that it is able to survive the acidic environment of the stomach and more effectively fight against bad bacteria and other harmful substances in the intestines. Similar to B. bifidum, one way it helps to keep the gut healthy is by binding to the intestinal cells in the intestines.

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