PhD project offered by the IMPRS-gBGC in July 2019

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Decoding the molecular signals of dissolved organic matter

Gerd Gleixner , Georg Pohnert

Project description

This project aims to give insight into the chemical diversity and metabolic activities in the Critical Zone.1,2 The overall research aim is to identify new marker compounds and general metabolic patterns for the elucidation of biogeochemical processes in this environment. Using these markers and patterns, the research focuses on answering the questions: which biological and environmental factors influence the molecular composition of dissolved organic matter (DOM)? Which metabolites and metabolic processes can be linked to DOM signatures? In order to answer these questions, samples obtained among different vegetation- and climatic zones under different land use will be analyzed. Thereby, this project will link microbial and abiotic drivers to the changing chemical signatures from the different sampling sites and under extreme climatic situations.
Within the project, advanced analytical techniques such as ultrahigh-resolution mass spectrometry3,4 and metabolite profiling5,6 will be applied to characterize the samples and to specifically single out marker molecules for structural and functional analysis.
The PhD candidate will be affiliated in the working group Molecular Biogeochemistry in MPI-BGC and in the Institute for anorganic and analytical chemistry in the FSU Jena. The successful PhD candidate will analyse the molecular properties of soil DOM using targeted and untargeted Orbitrap-MS techniques in order to answer “who” is doing “what” in soil and groundwater systems. Supervision at the MPI-BGC is provided by apl. Prof. Dr. Gerd Gleixner, Dr. Markus Lange and Prof. Dr. Georg Pohnert from the Friedrich Schiller University Jena. Additional expertize will be provided by Simon Benk (network analysis), Carsten Simon (fragmentation trees) and Dr. Carlos Sanchez-Arcos (metabolomics).

Requirements

Applications to the IMPRS-gBGC are open to well-motivated and highly-qualified students from all countries. For this particular PhD project we seek a candidate with
  • a Master's degree in Chemistry, Environmental Chemistry or other chemistry related sciences
  • experience in analytical chemistry, LC-MS, handling of big data sets
  • of advantage is experience in high resolution MS (FT-ICR-MS or Orbitrap-MS)
  • very good oral and written communication skills in English
The Max Planck Society seeks to increase the number of women in those areas where they are underrepresented and therefore explicitly encourages women to apply. The Max Planck Society is committed to increasing the number of individuals with disabilities in its workforce and therefore encourages applications from such qualified individuals.

References
  1. Küsel, K. et al. How Deep Can Surface Signals Be Traced in the Critical Zone? Merging Biodiversity with Biogeochemistry Research in a Central German Muschelkalk Landscape. Front. Earth Sci. 4, 32 (2016).
  2. Lange, M. et al. Plant diversity increases soil microbial activity and soil carbon storage. Nat. Commun. 6, 6707 (2015).
  3. Benk, S. A., Li, Y., Roth, V.-N. & Gleixner, G. Lignin Dimers as Potential Markers for 14C-young Terrestrial Dissolved Organic Matter in the Critical Zone. Front. Earth Sci. 6, 1–9 (2018).
  4. Simon, C., Roth, V.-N., Dittmar, T. & Gleixner, G. Molecular Signals of Heterogeneous Terrestrial Environments Identified in Dissolved Organic Matter: A Comparative Analysis of Orbitrap and Ion Cyclotron Resonance Mass Spectrometers. Front. Earth Sci. 6, 1–16 (2018).
  5. Kuhlisch, C. & Pohnert, G. Metabolomics in chemical ecology. Nat. Prod. Rep. 32, 937–955 (2015).
  6. Sanchez-Arcos, C., Kai, M., Svatoš, A., Gershenzon, J. & Kunert, G. Untargeted Metabolomics Approach Reveals Differences in Host Plant Chemistry Before and After Infestation With Different Pea Aphid Host Races. Front. Plant Sci. 10, 1–13 (2019).


(a) View of the central 325m tower at the Amazon Tall Tower Observatory (ATTO) in central Amazonia; (b) Aerial view of The Jena Experiment, the longest-running biodiversity experiments in Europe; (c) Front view of an LC-Orbitrap MS system; (d) Plot of molecular-level data of dissolved organic matter (DOM)<sup>4</sup>. The plot shows single molecular formulae (dots) according to their atomic ratios of hydrogen to carbon and oxygen to carbon (Van Krevelen plot), which gives insights into DOM’s reactivity and potential sources.
(a) View of the central 325m tower at the Amazon Tall Tower Observatory (ATTO) in central Amazonia; (b) Aerial view of The Jena Experiment, the longest-running biodiversity experiments in Europe; (c) Front view of an LC-Orbitrap MS system; (d) Plot of molecular-level data of dissolved organic matter (DOM)4. The plot shows single molecular formulae (dots) according to their atomic ratios of hydrogen to carbon and oxygen to carbon (Van Krevelen plot), which gives insights into DOM’s reactivity and potential sources.


>> more information about the IMPRS-gBGC + application