Dimethylsulfide membrane permeability, cellular concentrations and implications for physiological functions in marine algae

Dimethylsulfide (DMS) is an important component of the global sulfur cycle and a source of carbon and sulfur in marine ecosystems. However, cellular concentrations of DMS (DMSc) have never been quantified, despite being essential to evaluating its physiological functions. Herein, we used NMR to determine the permeability for DMS across the cell membrane in Thalassiosira pseudonana. The experimentally determined permeability of DMS (2.18+ 0.27 cm s at 300 K fell within the predicted permeability range for DMS (0.21–11.8 cm s) based on its octanol–water partition coefficient (18.6+ 1.1). Permeability was used with DMS fluxes to determine DMSc in three marine algal species. DMSc concentrations were ,1 nmol [Lcell volume] , which is inconsistent with several proposed physiological functions for DMS. At nM levels, DMSc may serve as an infochemical or another unknown function. Our results demonstrate that DMS is highly permeable through the cell membrane; the phycosphere will control the DMS flux into the dissolved phase, and as such the DMSc determined here is likely applicable to a wide range of marine algae. Ultimately, the permeability of DMS constrains DMSc and its cellular function(s), which are important in assessing the role of this compound in marine waters.