AME prepress abstract  -  DOI: https://doi.org/10.3354/ame01871

Do polar diatoms take up a quantitatively important fraction of dissolved dimethylsulfoniopropionate relative to bacteria?

Michel Lavoie*, Jeffrey C. Waller, Ronald P Kiene, Maurice Levasseur

*Email: Michel.lavoie.4@ulaval.ca

ABSTRACT: Dimethylsulfoniopropionate (DMSP) constitutes a major compound in the global sulfur cycle. A few studies over the last decade have revealed that not only bacteria, but also eukaryotic phytoplankton may take up DMSP from the dissolved pool although the mechanisms and quantitative importance of this undefined DMSP uptake pathway, particularly by polar phytoplankton remain poorly known. To fill this gap, we undertook short-term 35S-DMSP uptake kinetic experiments in axenic laboratory batch cultures of three polar marine diatoms (Thalassiosira gravida, Chaetoceros neogracilis, and Chaetoceros gelidus). DMSP uptake by C. neogracilis and C. gelidus was below the detection limit, but significant DMSP uptake by T. gravida was observed. These differences might be explained by the presence of a putative OpuD/DddT-like DMSP transporter in various Thalassiosira spp., which is absent in the transcriptomes of Chaetoceros spp. Based on conservative extrapolation of DMSP uptake kinetics measured in T. gravida cultures to the complex consortium of diatoms found in oligotrophic arctic environments, the fraction of dissolved DMSP taken up by polar diatoms is probably small compared to that taken up by bacteria and (perhaps) other eukaryotic algae.