Transcript 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
[email protected]
Overview
 Background –Marine sulphur cycle and DMS
 DMSO and why it is important.
 My research over the past few months.
 Preliminary study
 Future experiments
> 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
Background
red = DMS loss
pathway
green = DMS
production
pathway
Andrew Mogg
Hatton et al., 2004 Oceanography and Marine Biology: An Annual Review
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
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.
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?
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.
Preliminary study
 Measuring DMS, DMSO during a 2 week 30 mM enrichment
Average SqRt Area DMS
experiment under aerobic/anaerobic, L/D.
 DMS production higher in anaerobic light conditions than anaerobic
dark.
 Little difference between aerobic + L/ +D
1400
1200
1000
Anaerobic + L
800
Anaerobic + D
600
Aerobic + L
400
Aerobic + D
200
0
0
96
144
216
Time (hours)
288
336
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
Acknowledgements
Thanks to Angela Hatton, Arlene Ditchfield, Dave Green,
Andrew Mogg, Mark Hart, Neil Clark, Tosin Obata, Debbi
Brennan.