Environmental, biochemical and genetic drivers of DMSP degradation and DMS production in the Sargasso Sea

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Date
2011-10Author
Levine, Naomi M.
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Varaljay, Vanessa A.
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Toole, Dierdre A.
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Dacey, John W. H.
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Doney, Scott C.
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Moran, Mary Ann
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https://hdl.handle.net/1912/5074As published
https://doi.org/10.1111/j.1462-2920.2012.02700.xAbstract
Dimethylsulfide (DMS) is a climatically relevant trace gas produced and cycled by the
surface ocean food web. Mechanisms driving intraannual variability in DMS production and
dimethylsulfoniopropionate (DMSP) degradation in open-ocean, oligotrophic regions were
investigated during a 10 month time-series at the Bermuda Atlantic Time-series Study site in the
Sargasso Sea. Abundance and transcription of bacterial DMSP degradation genes, DMSP lyase
enzyme activity, and DMS and DMSP concentrations, consumption rates, and production rates
were quantified over time and depth. This interdisciplinary dataset was used to test current
hypotheses of the role of light and carbon supply in regulating upper-ocean sulfur cycling.
Findings supported UV-A dependent phytoplankton DMS production. Bacterial DMSP
degraders may also contribute significantly to DMS production when temperatures are elevated
and UV-A dose is moderate, but may favor DMSP demethylation under low UV-A doses. Three
groups of bacterial DMSP degraders with distinct intraannual variability were identified and
niche differentiation was indicated. The combination of genetic and biochemical data suggest a
modified ‘bacterial switch’ hypothesis where the prevalence of different bacterial DMSP
degradation pathways is regulated by a complex set of factors including carbon supply,
temperature, and UV-A dose.
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Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Environmental Microbiology 14 (2012): 1210-1223, doi:10.1111/j.1462-2920.2012.02700.x.