Accounting for 90% of ocean biomass, microorganisms form the foundation of the marine foodweb and are the engine-room for the chemical cycles that control our climate. However, human impacts, including pollution, modification and destruction of natural habitats and the influence of anthropogenically induced climate change have raised concerns about the future sustainability and welfare of marine ecosystems. Currently, we have limited knowledge of the effects of increased light irradiance on the phytoplankton population, bacterial community and chemical cycles. In particular the availability and uptake of the phytoplankton metabolite dimethylsulfonioproprionate (DMSP), which have been recently documented to drive many phytoplankton bacteria interactions. We have selected the coccolithophore Emiliania huxleyi to evaluate the effect of light and production of DMSP on the phytoplankton itself and on a natural bacterial assemblage.