apl. Prof. Dr. Gerd Gleixner
Senior Researcher and
for Organic Geochemistry at the
Friedrich Schiller University Jena
Phone: +49 (0)3641 57 6172
Terrestrial Organic Matter Cycling, Metabolic Isotope Fractionation, and Paleoclimate Reconstruction
We explore key processes in global biogeochemical cycles at the molecular level by using biomarkers and their isotopic content, which hold information on the regulation of individual processes. Our group also develops new tools and applies existing techniques to investigate single key processes.
Biomarkers are molecules that contain information about the presence of individual organisms in the environment. They span a variety of molecules with different chemical characteristics and are read using the “omic” approaches. Since nucleic acids are very easily decomposed in the environment, they provide only snapshots of actual communities. In contrast, lipids are compounds used to make cell membranes and cuticular waxes that can persist for a long time in the environment, and can even be isolated from Archaean rocks. Lipidomics is used to develop profiles that can identify individuals or groups of organisms as well as lipid profiles characteristic for environmental conditions including salinity, anoxia, and desiccation.
The key questions in molecular biogeochemistry are: Who is there, what are they doing, and why? Proteomic and metabolomic approaches allow us to address topics spanning from the presence of organisms to their function in the environment. However, in order to explore the function of individual processes and how the microbial fluxes link to the overall functioning of ecosystems, additional information is drawn from the isotopic information of biomarkers. Compound specific isotopes (13C, 14C, 15N, 18O and 2H) of biomarkers trace the flow of matter through element cycles. Our Molecular Biogeochemistry group combines approaches using the natural abundance of stable isotopes, isotope labeling, and stable isotope probing (SIP) to quantify key processes in the environment.
Easy-to-understand fact sheet of the group (pdf)
- Understanding the origin, fate and stability of organic matter in soils
- Understanding carbon flow in plant metabolism
- Understanding the role of biodiversity in biogeochemical cycles
- Understanding and reconstructing past climate and vegetation dynamics
Gerd Gleixner (2013): Soil organic matter dynamics: a biological perspective derived from the use of compound-specific isotope studies. Ecological Research, February 2013
Tefs C., G. Gleixner (2012): Importance of root derived carbon for soil organic matter storage in a temperate old-growth beech forest - evidence from C, N and 14C content. Forest Ecology and Management, 263, 131-137.
Steinbeiss S., G. Gleixner, M. Antonietti (2009): Effect of biochar amendment on soil carbon balance and soil microbial activity. Soil Biology and Biochemistry, 41, 1301-1310.
Steinbeiss S., V.M. Temperton, G. Gleixner (2008): Mechanisms of short-term soil carbon storage in experimental grasslands. Soil Biology and Biochemistry, 40, 2634-2642.
Sachse, D., J. Radke, G. Gleixner (2004): Hydrogen isotope ratios of recent lacustrine sedimentary n-alkanes record modern climate variability. Geochimica et Cosmochimica Acta, 68, 4877-4889.
Gleixner, G., N. Poirier, R. Bol, J. Balesdent (2002): Molecular dynamics of organic matter in a cultivated soil. Organic Geochemistry, 33, 357-366.
Gleixner, G., C.J. Czimczik, C. Kramer, B. Lühker, M.W.I. Schmidt (2001): Plant compounds and their turnover and stability as soil organic matter. In: Schulze, E.-D., Heimann, M., Harrison, S., Holland, E., Lloyd, J.L., Prentice, C., Schimel, D. (Eds.): Global Biogeochemical Cycles in the Climate System. Academic Press, San Diego, USA, 201-215.