Marine microorganisms are characterized by a very great functional and phylogenetic diversity. Because of their involvement in many steps of biogeochemical cycles, they are indispensable to life on earth. The Microbial Oceanography Laboratory (LOMIC, Sorbonne Université, CNRS) brings together expertise in the fields of marine biogeochemistry, microbial ecology, molecular diversity, physiology and genetics of model microorganism to investigate processes carried out by the ocean microbiome in elemental cycles. Ongoing carbon cycle research emphasizes the identification of important routes of carbon fluxes through microbial communities, with the goal of improving predictions of the fate of carbon in the context of a changing ocean. The study of the functions and diversity of marine microorganisms also offers interesting applications in the field of biotechnology, for example the production of high value-added molecules or the possibility of using certain microbial functions to degrade pollutants present in the oceans. This line of applied research is an integral part of the studies carried out at LOMIC.