HEOBI-METAT

Metal homeostasis stimulates prokaryotic trace metal trafficking on marine particlesAlong the co-evolution of marine microorganisms and biogeochemical cycles, trace metals were incorporated in all essential microbial metabolisms. In the present ocean, low metal concentrations can limit microbial growth whereas high concentrations can be toxic. The dissolved fraction is considered as the major bioavailable trace metal pool, while the particulate reservoir remains largely unexplored. Here we used a comparative metatranscriptomics approach to reveal that marine particles stimulate microbial processes involving trace elements. We show that particles enhance microbial trafficking of seven metals of biological importance. Overexpression of genes involved in the uptake of elements through various mechanisms demonstrate that particles are a bioavailable reservoir. But bacteria also invest in the transcription of genes controlling resistance to metal toxicity, storage, sensing and regulation. This intense trafficking driven by metal homeostasis provides clues that bacterial activity on particles is critical in the redistribution of trace metal between different fractions and chemical forms in the ocean.