Engineered probiotic bacteria could reduce obesity
6 Jan 2011
Irish scientists have found that specially designed probiotics
can modulate the physiology of host fat cells. The findings, published
in the journal Microbiology, could lead to specialised
probiotics that have a role in the prevention or treatment of conditions
such as obesity.
Scientists from the Alimentary Pharmabiotic Centre (APC), Cork,
University College Cork and Teagasc, in Ireland engineered a strain
of Lactobacillus to produce a version of a molecule called
conjugated linoleic acid (CLA). When this engineered bacterial
strain was fed to mice, the composition of the mice’s fat tissue was
significantly altered, demonstrating that ingesting live bacteria
can influence metabolism at remote sites in the body.
CLA is a fatty acid that is produced in different versions by
different bacteria. One type, called t10, c12 CLA, has been shown to
be associated with decreased body fat in humans and other animals.
t10, c12 CLA also has the ability to inhibit the growth of colon
cancer cells and induce their death. However, this type of CLA is
only produced by certain types of bacteria including
Propionibacterium acnes — a skin bacterium that can cause acne.
In this study, an enzyme-encoding gene from P. acnes was
transferred to the Lactobacillus strain allowing it to
produce t10, c12 CLA. Lactobacillus strains are common
inhabitants of the normal gut flora and are often found in probiotic
The researchers found that the level of t10, c12 CLA in the
mice’s fat tissue quadrupled when they were fed this recombinant
probiotic. Thus, this study demonstrates that gut microbes have an
impact on host metabolism, and in particular fat composition.
Dr Catherine Stanton, from Teagasc who led the study explained
the significance of the results: “CLA has already been shown to
alleviate non-alcoholic fatty liver disease that often accompanies
obesity. Therefore, increasing levels of CLA in the liver by
ingestion of a probiotic strain is of therapeutic relevance.
Furthermore, fat is not an inert layer around our bodies, it is
active and proinflammatory and is a risk factor for many diseases,
including cancers. The work shows that there is potential to
influence this through diet-microbe-host interactions in the gut.”
The same group of researchers previously found that microbially
produced CLA was able to reduce the viability of colon cancer cells
by 92%. “It is possible that a CLA-producing probiotic may also be
able to keep colon cancer cells in check. All our findings to date
demonstrate that the metabolism of gut bacteria can modulate host
cell activity in ways that are beneficial to the host,” explained Dr
Stanton. “We need to further investigate the effects of
CLA-producing bacteria on human metabolism, but our work so far
certainly opens up new possibilities for the use of probiotics for
improvement of human health.”
Eva Rosberg-Cody, Catherine Stanton, Liam O'Mahony, Rebecca Wall,
Fergus Shanahan, Eamonn Quigley, Gerald Fitzgerald and Paul Ross.
Recombinant lactobacilli expressing linoleic acid isomerase can
modulate the fatty acid composition of host adipose tissue in mice.
Microbiology, 2010. DOI: 10.1099/mic.043406-0