Manganese reduction coupled to the oxidation of ammonium and sulphur - a geochemical curiosity or an important biogeochemical process?
Lead Research Organisation:
CARDIFF UNIVERSITY
Department Name: School of Earth and Ocean Sciences
Abstract
While the contribution of organic matter oxidation to the biogeochemical cycles is well understood, a large number of putative lithotrophic processes has so far been overlooked but are assumingly widespread and important in the environment. Examples for these 'novel' processes are the oxidation of reduced sulphur species or ammonium coupled to manganese reduction, processes driven by the isolates investigated in this study. The manganese-dependent oxidation of ammonium produces nitrogen gas and may be responsible for 90% of the nitrogen loss in marine sediments. Investigating this process is, therefore, not only important for the understanding of the biogeochemical cycles. As nitrogen is removed from the system and not available for primary production, this type of anaerobic ammonium oxidation may play an important role in avoiding eutrophication, particularly in coastal areas. Similarly, manganese-dependent oxidation of sulphur compounds (elemental sulphur, thiosulphate) is a so far unknown process. However, it connects the element cycles of sulphur and oxygen in marine sediments and helps solving a major biogeochemical problem: the transfer of electrons from sulphide to oxygen spatially separated in different sediment layers. As these compounds are present also in subsurface sedments and aquifers they might also provide a basis for life for the 'Deep Biosphere'.
Publications
Parkes R
(2014)
A review of prokaryotic populations and processes in sub-seafloor sediments, including biosphere:geosphere interactions
in Marine Geology
Roussel EG
(2015)
Complex coupled metabolic and prokaryotic community responses to increasing temperatures in anaerobic marine sediments: critical temperatures and substrate changes.
in FEMS microbiology ecology
Watkins AJ
(2014)
Glycine betaine as a direct substrate for methanogens (Methanococcoides spp.).
in Applied and environmental microbiology
Watkins AJ
(2012)
Choline and N,N-dimethylethanolamine as direct substrates for methanogens.
in Applied and environmental microbiology
Webster G
(2019)
Genome Sequences of Two Choline-Utilizing Methanogenic Archaea, Methanococcoides spp., Isolated from Marine Sediments.
in Microbiology resource announcements
Webster G
(2010)
Prokaryotic functional diversity in different biogeochemical depth zones in tidal sediments of the Severn Estuary, UK, revealed by stable-isotope probing.
in FEMS microbiology ecology
Description | During the project the disappearance of ammonium in anoxic sediments was observed but did not show a clear correlation with any other process. In pure culture experiments members of the genus Desulfosporosinus (strictly anaerobic bacteria) converted ammonium into methylamine under certain conditions, e.g. in the presence of compounds like choline and betaine which are very widespread biomolecules. This is a completely new metabolic pathway and was unexpected. |
Exploitation Route | The results obtained with the Desulfosporosinus spp. are currently written up. Slurry experiments are publiushed. The results from cultures with manganese and ammonium need additional runs to confirm the results. We would like to do that ourselves. |
Sectors | Education,Environment |
Description | Prof. George Luther, manganese |
Organisation | University of Delaware |
Country | United States |
Sector | Academic/University |
PI Contribution | Analysis of managanese rich sediments. |
Collaborator Contribution | Introduction of voltametric electrode system. |
Impact | The voltammetric electrodes were not as specific as hoped and this method was not pursued further. |
Start Year | 2008 |