1. Susan Evans, David Green and Angela Hatton
Dimethylsulphoxide (DMSO) loss pathways in the ocean: The next question in DMS biogeochemistry.
Susan Evans, David Green and Angela Hatton

2. Overview Background –Marine sulphur cycle and DMS
DMSO and why it is important.
My research over the past few months.
Preliminary study
Future experiments

3. Hatton et al., 2004 Oceanography and Marine Biology: An Annual Review
> 90% of the oceanic sulphur flux and > 50% of the global flux (Andreae, 1986)
Hatton et al., 2004 Oceanography and Marine Biology: An Annual Review

4. Background red = DMS loss pathway green = DMS production pathway
Andrew Mogg

6. Hatton et al., 2004 Oceanography and Marine Biology: An Annual Review

7. DMSO importance
DMSO is the dominant dimethylated sulphur species throughout the column (Hatton et al., 1994) .
Production pathways:
photoxidation of DMS
atmospheric deposition
synthesis and release from algal cells.
Hatton et al., 2004 Oceanography and Marine Biology: An Annual Review

8. DMSO loss pathways Microbial utilisation
Chemical oxidation to dimethylsulphone
Biological reduction to DMS
Variety of bacteria are capable of anaerobic growth in the presence of DMSO as the terminal electron acceptor (Zinder & Brock., 1978).
Spiese et al, (2009) suggest that DMSOp reduction may be an important source of DMS from algae.

10. Initial questions
Does DMSO represent an important carbon source for marine bacteria?
Is DMSO reduction, as an alternative electron acceptor to oxygen, a viable or key process in the marine environment?
What are the key microbes involved in the production and removal of DMSO?
Which environmental factors will influence the rates of production and removal of DMSO?
Do algal associated bacteria play a role in the removal of DMSO for the marine system?

11. The last few months.
Figure 2.1: Apparatus for measurement of DMS. The sample preparation system consisted of 1. Oxygen-free nitrogen purge gas, 2. Flow control valve, 3. Purge tube, inlet with luer valve and glas frit, 4.glass tubing with glass wool. 5. Nafion dryer encased in molecular sieve type 13 x, 6. 6 port sample injection valve. 7. Sample loop 8. Resistor element. 9. Thermocouple 10. Cryotrap dewar containing liquid nitrogen. 11. Temperature controller 12. Exhaust line for flow measurements 13. GC column. 14. Detector 15. Laptop with VarianStar analysis package.

12. Preliminary study
Measuring DMS, DMSO during a 2 week 30 mM enrichment experiment under aerobic/anaerobic, L/D.
DMS production higher in anaerobic light conditions than anaerobic dark.
Little difference between aerobic + L/ +D

13. Future work Denaturing gradient gel electrophoresis (DGGE)
Fluorescent in-situ hybridization (FISH) analysis
Sequencing
Stable isotope probing (SIP) with C13.
Enrichment experiment with DSS-3 Rugeria/Sillicibacter pomeroyi.
Methanogenic archeae and DMSO as a substrate? Zindler et al., 2012

14. Acknowledgements
Thanks to Angela Hatton, Arlene Ditchfield, Dave Green, Andrew Mogg, Mark Hart, Neil Clark, Tosin Obata, Debbi Brennan.