AIMS@JCU, James Cook University, Townsville, Australia; Australian Institute of Marine Science, Townsville, Australia; Climate Change Cluster, University of Technology Sydney, Sydney, Australia; ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Australia; College of Science and Engineering, James Cook University, Townsville, Australia
Peta L Clode
The Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Crawley, Australia; Oceans Institute, The University of Western Australia, Crawley, Australia
Soshan Cheong
Mark Wainwright Analytical Centre, University of New South Wales, Kensington, Australia
Jeremy Bougoure
The Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Crawley, Australia; School of Earth and Environment, The University of Western Australia, Crawley, Australia
Matt R Kilburn
The Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Crawley, Australia
Anthony Reeder
The Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Crawley, Australia
ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Australia; Research School of Biology, Australian National University, Canberra, Australia
Michael Stat
Trace and Environmental DNA Laboratory, Department of Environment and Agriculture, Curtin University, Perth, Australia
Victor Beltran
Australian Institute of Marine Science, Townsville, Australia
Peter Thomas-Hall
Australian Institute of Marine Science, Townsville, Australia
Dianne Tapiolas
Australian Institute of Marine Science, Townsville, Australia
Cherie M Motti
AIMS@JCU, James Cook University, Townsville, Australia; Australian Institute of Marine Science, Townsville, Australia
Bill Gong
Mark Wainwright Analytical Centre, University of New South Wales, Kensington, Australia
Mathieu Pernice
Climate Change Cluster, University of Technology Sydney, Sydney, Australia
Christopher E Marjo
Mark Wainwright Analytical Centre, University of New South Wales, Kensington, Australia
Justin R Seymour
Climate Change Cluster, University of Technology Sydney, Sydney, Australia
Bette L Willis
AIMS@JCU, James Cook University, Townsville, Australia; ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Australia; College of Science and Engineering, James Cook University, Townsville, Australia
David G Bourne
Australian Institute of Marine Science, Townsville, Australia; College of Science and Engineering, James Cook University, Townsville, Australia
Phytoplankton-bacteria interactions drive the surface ocean sulfur cycle and local climatic processes through the production and exchange of a key compound: dimethylsulfoniopropionate (DMSP). Despite their large-scale implications, these interactions remain unquantified at the cellular-scale. Here we use secondary-ion mass spectrometry to provide the first visualization of DMSP at sub-cellular levels, tracking the fate of a stable sulfur isotope (34S) from its incorporation by microalgae as inorganic sulfate to its biosynthesis and exudation as DMSP, and finally its uptake and degradation by bacteria. Our results identify for the first time the storage locations of DMSP in microalgae, with high enrichments present in vacuoles, cytoplasm and chloroplasts. In addition, we quantify DMSP incorporation at the single-cell level, with DMSP-degrading bacteria containing seven times more 34S than the control strain. This study provides an unprecedented methodology to label, retain, and image small diffusible molecules, which can be transposable to other symbiotic systems.
