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PhD Dissertation: The role of microorganisms in the cycling of organic matter in anoxic marine environments: A culture-independent approach

All life on earth is dependent on the processes performed by unicellular lifeforms. In the oceans, they largely regulate the cycles of nutrients and carbon that are vital for life on earth. In the marine carbon cycle, algae and other autotrophic organisms fix inorganic carbon to organic molecules like cellulose and starch. While a majority of this organic matter is recycled to inorganic carbon in the water column, some of it is buried in sediments. This organic matter acts as an important link between rapid carbon cycling in the biosphere and long-term carbon storage.

The amount of organic matter that is recycled or stored in sediments, depends on environmental conditions like depth of the water column and oxygen concentrations. More organic matter is stored under oxygen-depleted conditions. Oxygen depletion strongly effects the metabolism of microbial communities in marine environments, which is probably one of the main factors impeding organic matter recycling. Most of the microorganisms in anoxic marine environments are known only through genetic information; their metabolisms and the dynamics affecting organic matter cycling remain unknown.

Further information on the activities and interactions of microorganisms in anoxic conditions may help in understanding the limits and future development of the marine carbon cycle. The objective of this thesis was to study the relationship of microbial metabolism to organic matter cycling in anoxic environments. The results highlight the function of abundant uncultured members of microbial communities, as well as the importance of the organic matter composition in shaping microbial communities across anoxic water columns and sediments.

Start date and time
End date and time
PhD candidate
Saara-Maija Tuulikki Suominen
Dissertation
The role of microorganisms in the cycling of organic matter in anoxic marine environments: A culture-independent approach
PhD supervisor(s)
Prof. Dr. J.S. Sinninghe Damste
Prof. Dr. S. Schouten
Co-supervisor(s)
Dr. L. Villanueva