Role of cloud microorganisms in atmospheric processes
10 years ago our group started to study microorganisms present in cloud waters at the Puy de Dôme station. We showed that they were alive and metabolically active because they can resist to atmospheric stresses. This pioneering work opened new scientific questions concerning their potential role in atmospheric chemistry and physics. We showed that microorganisms can act as an alternative route to radical chemistry to transform organic compounds and oxidant species (including hydrogen peroxide and Iron) in clouds. Cloud microorganism can also participate to the formation of droplets by the production of biosurfactants, some others can act as Ice Nuclei thanks to their membrane protein and could thus participate to precipitations. Recent results will be presented.