Discovery of 'probiotic transporters' unlocks secrets of infection-preventive bifidobacteria

Jan 26, 2011
Survival rate of germ-free mice, preventive B. longum (BL)- and non-preventive B. adolescentis (BA)-associated mice after O157 infection (n = 10).

Japanese researchers at RIKEN, Yokohama City University and the University of Tokyo have uncovered how gut bifidobacteria protect the body against lethal infection by enhancing the defenses of colonic epithelium. Published in this week’s issue of Nature, the finding provides first-ever clues on the mechanisms underlying the beneficial effects of gut microbiota, promising more effective probiotic therapies for a variety of disorders and diseases.

In recent years, new metagenomics techniques have enabled scientists to delve ever-deeper into the world of gut microbiota, revealing the strong influence that intestinal exert on our health. Bifidobacteria, one of the most numerous such bacteria, confer to their hosts a range of beneficial health effects, aiding in digestion, boosting the immune system and even reducing cancer risk. The mechanism underlying these effects, however, has remained a mystery.

With their study, the research team set out to unravel this mystery using a combination of techniques from genetics, transcriptomics and metabolomics. Initial experiments on so-called germ-free (GF) mice, whose guts are uncolonized by bacteria, revealed stark differences between bifidobacteria strains. The researchers found that mice colonized by one bifidobacterium subspecies, B. longum, were able to survive when fed the pathogenic bacteria E. coli O157, while GF mice without the bacteria died of infection within 7 days. Another strain named B. adolescentis, in contrast, had no such effect.

Schematic representation of the mechanisms of O157 lethal infection and prevention by bifidobacteria. Both B. longum (BL) and B. adrescentis (BA) possess glucose transporter(s) and can produce acetate from glucose in the proximal colon, where glucose is thought to be present; this acetate exerts an anti-apoptotic effect on colonic epithelium. In the distal colon, in contrast, only fructose is available, and thus only BL, with its fructose transporters, is able to produce acetate there. BA lacks the fructose transporters, and thus fails to produce enough acetate to prevent epithelial apoptosis by O157. This results in translocation of Shiga toxin into the blood stream, leading to death of the mice.

By analyzing fecal metabolic profiles, the researchers succeeded in pinpointing the source of this difference in the production of acetate, which they showed enhances intestinal epithelial defense and protects against infection from O157. The key actor in this mechanism is a carbohydrate transporter encoded by genes present in certain strains of bifidobacteria such as B. longum, which enables these bacteria to utilize fructose to produce acetate in the distal colon.

As a demonstration of the power of multi “omics” technologies, the identification of these “probiotic transporters” constitutes a milestone in the study of gut microbiota. The finding also demonstrates the power of multi “omics” technologies for analyzing the gut ecosystem, promising advancements in the development of cutting-edge probiotic therapies.

Explore further: First structural insights into how plant immune receptors interact

More information: Shinji Fukuda, Hidehiro Toh, Koji Hase, Kenshiro Oshima, Yumiko Nakanishi, Kazutoshi Yoshimura, Toru Tobe, Julie M. Clarke, David L. Topping, Tohru Suzuki, Todd D. Taylor, Kikuji Itoh, Jun Kikuchi, Hidetoshi Morita, Masahira Hattori and Hiroshi Ohno. Bifidobacteria protect host from enteropathogenic infection through production of acetate. Nature (2010). DOI: 10.1038/nature09646

add to favorites email to friend print save as pdf

Related Stories

Gut bacteria can cause obesity

Feb 12, 2010

Diet, exercise and genes are not the only factors which determine if someone can become obese. The composition of the intestinal bacteria may also account for a person's obesity. This is the contention of Wageningen microbiologists ...

Bacteria help infants digest milk more effectively than adults

Nov 22, 2010

Infants are more efficient at digesting and utilizing nutritional components of milk than adults due to a difference in the strains of bacteria that dominate their digestive tracts. Researchers from the University of California, ...

Cancer-causing gut bacteria exposed

Sep 22, 2008

Normal gut bacteria are thought to be involved in colon cancer but the exact mechanisms have remained unknown. Now, scientists from the USA have discovered that a molecule produced by a common gut bacterium activates signalling ...

Resistant gut bacteria will not go away by themselves

Jun 19, 2007

E. coli bacteria that have developed resistance to antibiotics will probably still be around even if we stop using antibiotics, as these strains have the same good chance as other bacteria of continuing to colonise the gut, ...

Recommended for you

Deadly human pathogen Cryptococcus fully sequenced

12 hours ago

Within each strand of DNA lies the blueprint for building an organism, along with the keys to its evolution and survival. These genetic instructions can give valuable insight into why pathogens like Cryptococcus ne ...

Building better soybeans for a hot, dry, hungry world

Apr 16, 2014

(Phys.org) —A new study shows that soybean plants can be redesigned to increase crop yields while requiring less water and helping to offset greenhouse gas warming. The study is the first to demonstrate ...

User comments : 0

More news stories

Scientists tether lionfish to Cayman reefs

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

Deadly human pathogen Cryptococcus fully sequenced

Within each strand of DNA lies the blueprint for building an organism, along with the keys to its evolution and survival. These genetic instructions can give valuable insight into why pathogens like Cryptococcus ne ...

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

Leeches help save woman's ear after pit bull mauling

(HealthDay)—A pit bull attack in July 2013 left a 19-year-old woman with her left ear ripped from her head, leaving an open wound. After preserving the ear, the surgical team started with a reconnection ...

Venture investments jump to $9.5B in 1Q

Funding for U.S. startup companies soared 57 percent in the first quarter to a level not seen since 2001, as venture capitalists piled more money into an increasing number of deals, according to a report due out Friday.