Bacterial community life (1), counting and adapting quorum sensing

The third lecture was entitled "Bacterial community life, counting and adapting: quorum sensing ". The aim of this lecture was to decipher the molecular mechanisms involved in maintaining bacterial communities, whether monomicrobial (the exception) or multimicrobial (the rule). Bacteria count and adapt to their own density through the production and perception of small molecules, the autoinducers, essentially derivatives of lactone-functional molecules in Gram-negative bacteria and small peptides in Gram-positive bacteria. This lecture showed that these basic mechanisms of microbial community life exist in an infinite number of situations, including colonization processes during human infections. This lecture was complemented by a seminar given by Jonathan Ewbank (CIML, Marseille), one of the world's leading specialists in the study of microbial pathogenicity mechanisms in the worm Caenorhabtidis elegans. As in the case of Drosophila, this lecture demonstrated the power of alternative models that are simpler and easier to subject to global genetic analysis for the study of very fundamental life mechanisms such as the management of the host-microbe interface, many components of which, as far as the innate part of the response is concerned, have been conserved and largely "recycled" during evolution.