Lactobacillus: a life partner…

Lactobacillus is a type of bacteria that has been used in food for centuries. Indeed they are responsible for the conversion of milk into cheese or yoghourt. Some of the bacteria that we found in our day-to-day diet can be called probiotics* when they are considered to have a beneficial impact on the person that consume them. Lactobacillus can also be found in food supplements or in specially enriched food, also referred to as functional food.
Lactobacilli are naturally present in our body and concentrate in the large intestine and vagina where they cohabit with hundreds of other types of bacteria. They are known for their protective action against infections caused by bacterial pathogens. This is why it can be beneficial to increase their concentration in the digestive track by consuming probiotics. The identified mechanisms of action include:

  • Production of antibiotics (molecules designed to target and kill other bacteria)
  • Competition for adhesion sites that prevent pathogens to attach to the intestinal wall and infect the body
  • Increased acidity of the environment that makes it less attractive for pathogens


*Probiotics are defined by the International Scientific Association for Probiotics and Prebiotics (ISAPP) as ‘live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host’. Click here to be redirected to the Probiotics Consumer Information page provided by the ISAPP.

More than protecting us against infection…

In the UK 62% of the adult population is considered overweight or obese. Obesity increases dramatically the risk of developing metabolic disorders such as type 2 diabetes, which is characterized by a loss of control over blood sugar level. Many studies have now linked this condition to an altered gut bacteria population, indicating that a link may exist between the type of bacteria present in our large intestine and obesity.
In addition, several research groups have shown that the consumption of Lactobacillus-based probiotics by obese individuals was beneficial as it reduced the risk to develop further complications. However, the mechanisms by which Lactobacillus may provide those effects have yet to be clarified. Adding to the complexity of this relationship, every single species of Lactobacillus expresses a slightly different set of genes, which makes it unique. Today, over 180 species of Lactobacillus have been identified. It is therefore difficult to untangle the exact contribution of every bacteria, as they potentially all interact in different ways with their host. We therefore try to understand which Lactobacillus can really enhance health benefits for a specific individual. Ultimately, we hope that this research will result in the development of personalized functional food.
Probiotics benefits

Improving our understanding of Lactobacillus

In our laboratory, we conduct research that aim at understanding how Lactobacillus bacteria can enhance health.

Lactobacillus and ageing

Ageing is associated with an alteration of the gut bacterial population that has been linked to a reduced activity of defense mechanisms and some metabolic alterations. In a study conducted in partnership with the University of Tartu (Estonia), we evaluated whether the intestinal population of Lactobacillus affected elderly metabolism. Using a recent technique relying on metabolic fingerprinting of intestinal content (measured in feces), our results indicated that some Lactobacillus were strongly correlated with the amount of chemicals that serve as a source of energy for intestinal and liver cells. More research in this area may contribute in the future to develop probiotic-containing products that improve the overall health condition of an increasingly aging population.
For more details: Le Roy, C. I., Štšepetova, J., Sepp, E., Songisepp, E., Claus, S. P., & Mikelsaar, M. (2015). New insights into the impact of Lactoacillus population on host-bacteria metabolic interplay. Oncotarget, 1–12.Free text

Probiotics for farm animals

The constant use of antibiotics in industrial farms for the last decades has raised concerned about the potential development of microbial resistance. It is therefore urgent to find new alternatives to replace antibiotics and efficiently protect farm animals against infections. We evaluate the potential of a Lactobacillus bacterium, Lactobacillus reuteri, to protect chicken against infection by a common pathogen (Brachyspira pilosicoli). To do so we used a cellular model to evaluate whether L. reuteri was able to protect intestinal cells against B. pilosicoli infection. We also determined whether both infection and Lactobacillus had an impact on cell metabolism.