Scientists at research institute Teagasc and University College Cork 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, they found the composition of the mice’s fat tissue was significantly altered, suggesting 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 associated with decreased body fat in humans and other animals. 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, which was published in the journal Microbiology, an enzyme-encoding gene from Propionibacterium acnes was transferred to the Lactobacillus strain allowing it to produce t10, c12 CLA. The researchers found that the level of t10, c12 CLA in the mice’s fat tissue quadrupled when they were fed this recombinant probiotic. This demonstrated that gut microbes have an impact on host metabolism, and in particular fat composition, they said.
Teagasc researcher Catherine Stanton, who led the study explained: “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 percent. “It is possible that a CLA-producing probiotic may also be able to keep colon cancer cells in check,” said Stanton. “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. 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, Dec 22, 2010 DOI: 10.1099/mic.0.043406-0