<p> Understanding the enzyme mechanisms of bacteria in gut microbiota to develop new molecules against antibiotic resistance, is one of Olivier Berteau’s pet subjects at the Institute for Food Microbiology for Human Health (MICALIS - Université Paris-Saclay, INRAE, AgroParisTech). This specialist in the biochemistry of microbiota has been awarded an ERC grant for the third time in the Proof of concept category for his ENTRAP project.</p> <p> The resistance of some bacteria to antibiotics, also known as antibiotic resistance, has become a major public health issue as it is responsible for tens of thousands of deaths per year in Europe. In France alone, antimicrobial resistance is responsible for at least 5,500 deaths per year. The phenomenon of resistance is linked to the misuse of antibiotics in particular. In 2015, the World Health Organization (WHO) warned about the need to optimise the use of antimicrobial drugs, as well as strengthen the research and development of new and effective compounds. Olivier Berteau and his Chemistry and synthetic biology (ChemSyBio) team at the Micalis Institute have been dedicating their work to this area through the study of bacteria in gut microbiota.</p> <p> A health problem with an alarming scenario</p> <p> Antibiotic resistance is when an antibiotic treatment is no longer effective against a bacterial infection. Normally, antibiotic treatment neutralises the bacteria responsible for the infection and only a minor amount of resistant bacteria survives in the gut. The repeated administration of antibiotics or their inappropriate use can lead to the prevalence of resistant bacteria. The overuse of antibiotics in particular triggers a ‘selective pressure’ in the body which favours the mutation and multiplication of these bacteria.</p> <p> When resistance arises from chromosomal mutations in the bacteria’s DNA, the resistance applies to only one antibiotic or family of antibiotics. However, in 80% of cases, antibiotic resistance is linked to the acquisition of genetic material by ‘conjugation’, i.e. the exchange of plasmids from a donor bacterium to a recipient bacterium. The genetic information carried by the plasmids, such as antibiotic resistant genes, can then be transferred from one bacterium to another.</p>