Julia van Winden

PhD Thesis Defence: 4 November 2011 14.30
Academiegebouw Utrecht, Domplein 29, Utrecht

Methane cycling in peat bogs:
Environmental relevance of methanotrophs
revealed by microbial lipid chemistry

mail@juliavanwinden.nl
Supervisor: Gert-Jan Reichart
Promotor: Jaap Sinninghe Damsté
Department of Earth Sciences, Utrecht University,
The Netherlands

About methane cycling in peat bogs:

Sphagnum, peat moss, dominates in rain-fed raised bogs, where nutrients are solely supplied via precipitation. To gain nutrients, Sphagnum efficiently transfers nutrients for protons, acidifying its own environment. Due to the low pH and low nutrient availability, degradation of the organic matter occurs very slowly. Peat bogs dominated by Sphagnum are therefore important net accumulators of organic matter, storing up to 30% of the carbon sequestered in soils globally. This is three times as much as the amount of carbon stored in tropical rainforests. Wetlands in general are responsible for 80% of the natural methane flux to the atmosphere, a strong greenhouse gas. Most of the methane produced in peat bogs, however, is consumed by methanotrophic bacteria. Molecular probes have shown that these methanotrophs live as partly endophytic symbionts in Sphagnum mosses from the Mariapeel in The Netherlands (Raghoebarsing et al., Nature, 2005). To gain insight into the significance of the symbiosis between methanotrophic bacteria and Sphagnum on a global scale, Sphagnum mosses from peatlands all over the world were collected and tested for methane oxidation activity. The importance of aerobic methane oxidation for the availability of CO₂ for photosynthesis by Sphagnum is established by monitoring the methane-derived label incorporation into specific lipids of Sphagnum (triterpenoids, sterols, n-alkanes). This is done in close collaboration with Nardy Kip from the Radboud University, who takes care of the microbiological part of this project. The assessment of the impact of past and future environmental change on the activity of methanotrophs in peat bogs is crucial for an accurate understanding of the global carbon cycle. Therefore, Sphagnum mosses are analyzed for the occurrence of methanotroph biomarkers (hopanoids), to enable studying past methane cycling in peats, unravelling the influence of environmental controls on the functioning of the methane cycle.

Publications

N. Kip#, J.F. van Winden#, Y. Pan, L. Bodrossy, G.-J. Reichart, A.J.P. Smolders, M.S.M. Jetten, J.S. Sinninghe Damsté and H.J.M. Op den Camp (2010) Global prevalence of methane oxidation by symbiotic bacteria in peat moss ecosystems. Nature Geoscience 3, 617-621. #Contributed equally

J.F. van Winden, N. Kip, G.-J. Reichart, M.S.M. Jetten, H.J.M. Op den Camp and J.S. Sinninghe Damsté. (2010) Lipids of symbiotic methane-oxidizing bacteria in peat moss studied using stable carbon isotopic labelling. Organic Geochemistry 41, 1040-1044.

A.V. Brader, J.F. van Winden, S.J.P. Bohncke, C.J. Beets, G.J. Reichart and J.W. de Leeuw (2010) Fractionation of hydrogen, oxygen and carbon isotopes in n-alkanes and cellulose of three Sphagnum species. Organic Geochemistry 41, 1277-1284.

N. Kip, W. Ouyang, A.A. Raghoebarsing, J.F. van Winden, L. van Niftrik, A. Pol, Y. Pan, L. Bodrossy, E.G. van Donselaar, G.J. Reichart, M.S.M. Jetten, J.S. Sinninghe Damsté and H.J.M. op den Camp (2011) Detection, isolation and characterization of acidophilic methanotrophs from Sphagnum mosses. Applied and Environmental Microbiology, DOI: 10.1128/AEM.05017-11.

Selected Presentations

Oral presentations:
BIOGEOMON, Helsinki, 2009, Award Winning
IMOG, Bremen, 2009
NSG, Amsterdam, 2009
Invited lecture, Newcastle University, 2009
Darwin Days & NAC10, Veldhoven, 2010
EGU, Vienna, 2010

Posters:
Darwin Days & NAC9, Veldhoven, 2008, Award Winning
NSG, Utrecht, 2008, TNO-poster Award
EGU, Vienna, 2009.

Visits & Fieldwork

Within my PhD research I have worked together with Newcastle University, UK, AWI Bremerhaven, Germany and the CEH in Lancaster, UK, and carried out field research in Flordia, US, and in Moorhouse, UK.

Teaching

Teaching assistant: Paleoceanography, Masters course (2007-2010)

Currently I work at: Shell Global Solutions International B.V.