The Gut and oral cavity are parts of the human body that accommodate thousands of different bacterial species. These bacteria, often beneficial for human health, are continuously in a stressful environment and compete with each other for food and space. Johann Mignolet, researcher in the team of Prof. Pascal Hols, has demonstrated that Streptococcus salivarius, a bacterium living peacefully in the human gut, uses a communication pheromone to concomitantly trigger two responses: the ability to modify its genome via the acquisition of "foreign" DNA and the production of antibacterial toxins (bacteriocins). These toxins or non-transformable variants of S. saliviarius could be used for medical purposes to kill harmful multi-resistant superbugs such as Staphylococcus aureus and some enterococci and streptococci.