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Microbial degradation of DMS/DMSO/DMSP in the marine environment

  • Is bacterial DMS consumption dependent on methylamines in marine waters? NERC (2018-2021)

Dimethylsulfide (DMS) is a key ingredient in the cocktail of gases that makes up the 'smell of the sea'. However, most of the DMS formed in the oceans stays there, facing consumption by marine microbes and conversion to another sulfur compound - dimethylsulfoxide (DMSO). We have found a previously unrecognised and intriguing link between the bacterial breakdown of organic nitrogen compounds, like methylamines, and organic sulfur compounds like DMS. This link is provided by a bacterial enzyme called trimethylamine monooxygenase (TMM). TMM simultaneously removes both methylamines and DMS from seawater (converting it to DMSO). We will determine the importance of this process compared to other biological processes that consume DMS in seawater and put names to the microbes using this enzyme to remove DMS. We will study the microbial processes linking the organic sulfur and nitrogen cycles in the English Channel at a station that is sampled weekly as part of the Western Channel Observatory which is coordinated by Plymouth Marine Laboratory. Given the important role of DMS, identifying the role of marine microorganisms and the pathways of DMS removal from seawater will provide key information that will improve our future understanding of how the sulfur cycle influences our climate.

Postdoctoral research fellow: Dr Jess Palmer.

Principle investigator: Dr Hendrik Schafer, Co-investigator: Dr Yin Chen

  • SIMbRICS: Sea Ice Microbiology and the Role In Cycling of Sulfur (DMS, DMSP, DMSO, MT) NERC (2019-2022)

The Arctic Ocean is undergoing unprecedented changes as the Earth warms due to climate change. Increasing global temperatures are resulting in increased rates of glacial melting and retreat, thawing of the permafrost and a steady trend towards reduced sea ice extent in winter. In Autumn 2019, the German Icebreaker FS Polarstern is undertaking a unique expedition, to sail to the edge of the Arctic sea ice in the Russian Laptev Sea, and allow the sea ice to form around the ship. This project has been designed as a key part of this expedition, and will study the formation of a gas called dimethylsulfide (DMS), a key ingredient in the cocktail of gases that makes up the 'smell of the sea'. Our project aims to investigate the changes in the microbial (bacterial and algal) community across the seasonal changes in the Arctic, and to look at how these changes affect the production rates of DMS and associated organic sulfur compounds. To this end, we will undertake 2 months stationed on FS Polarstern during the boreal spring, and form international collaborations to extend our sample availability to over 6 months through spring to summer. We will continue our research in the home laboratory by studying so-called 'model micro-organisms' which we will collect during our time at sea (or in the ice!). All our data collected in the Arctic will be compared to our previous studies in the Antarctic, to give a much clearer picture of the importance of the polar regions as a source of DMS, and how climate change will affect our global climate as these areas change.

Postdoctoral research fellow: Dr Alison Webb.

Principle investigator: Dr Hendrik Schafer, Co-investigator: Prof Jon Todd, Dr Yin Chen

  • Microbial degradation of dimethylsulfoxide in the marine environment. NERC (2014-2017)

Dimethylsulfoxide (DMSO) is a chemical with a wide range of applications. It is a widely used solvent, for instance in pharmaceutical applications, and a waste product of the paper milling industry. It also occurs naturally in a range of fruits, like raspberries, and vegetables. However, DMSO is also a compound that is part of the natural sulphur cycle. Sulphur is an essential element for all life, and in its organic form is a component of all proteins such as the amino acids cysteine and methionine. DMSO is an organic sulphur compound found everywhere in our oceans, and is produced by a number of natural biological and chemical processes. DMSO is important because it is both a source and a sink for a climate-cooling gas called dimethyl sulfide (DMS). DMS is a component of the smell of the seaside. Around 300 million tons of DMS are made each year by marine microorganisms. Some of this DMS is released into the atmosphere above the oceans, where it reacts in air to compounds that seed clouds, which is suggested influences weather and climate. When it rains, sulphur compounds are deposited back into the soils of our continents. However the majority of the DMS formed in the oceans is thought not to be released to the atmosphere, but rather to be converted to DMSO, and thus stays in seawater. However what happens to this DMSO largely remains a mystery which will be characterized in this project.

Postdoctoral research fellow: Dr Jason Stephenson.

Principle investigator: Dr Hendrik Schafer, Co-investigator: Dr Yin Chen