PhD STUDENT POSITION (4 year tenure): "Microbial use of terrestrial carbon in aquatic and terrestrial ecosystems"
The atmospheric CO2 concentration had doubled by 2010 compared to preindustrial levels, and by 2050 it is projected to have tripled. This anthropogenic influence is expected to lead to severe climate consequences. An important source for atmospheric CO2 is the decomposition of terrestrial carbon (C), composed of e.g. plant material. The processing of terrestrial C is divided about equally between terrestrial and aquatic ecosystems, and its decomposition is dominated by microorganisms. Thus, the microbial C-use is a critical parameter to predict the exchange of terrestrial C with atmospheric CO2. The first step that will determine whether the microbial use of terrestrial C will be a net sink or source to atmospheric CO2 is their C-use efficiency: how C is partitioned between catabolic (respiration) and anabolic (growth) processes. Alarmingly, this remains under-explored for terrestrial microorganisms. In aquatic environments, in contrast, the balance between microbial respiration and growth is a mature research field. We will use the tools, concepts and accumulated understanding from aquatic systems and employ them in a terrestrial application. In addition, we will conduct the first explicit, and systematic, comparison of the C-use of decomposer microorganisms - the food-web foundation - in aquatic and terrestrial ecosystems. Through international collaboration we will assess how microorganisms use a quality gradient of terrestrial C - from field experiments where e.g. warming, pH and N fertilisation has affected the organic matter. In aquatic and terrestrial microcosm systems we will employ isotopic methods to determine the microbial C allocation between growth and respiration, and provide estimates of this critical parameter for the modelling of the microbial C-feedback to environmental change. In addition to comparing the terrestrial C-use in aquatic and terrestrial ecosystems we will also investigate if C-use links differently to the microbial community composition in the two ecosystem types. You will be working with Associate professor Johannes Rousk´s group ( http://www4.lu.se/microbial-ecology/people/senior-scientists/johannes-rousk ) within the larger the multidisciplinary research program Molecular Interactions Controlling soil Carbon Sequestration –MICCS. The overall goal of this program is to gain a mechanistic understanding of the interactions between soil organic matter (SOM), the activity of decomposing microorganisms and the physicochemical environment that control the stability of SOM. The MICSS research environment consists of a strong team of scientists, research technicians, post docs and PhD students studying these interactions at different complexity and spatial scales – from defined model systems to field sites – using cutting-edge technology ranging from spectroscopic analysis to transcriptome profiling, isotope labelling, and systems biology methods. We are presently recruiting 4 postdoctoral fellows and 6 PhD students to the research program. To learn more, please visit our webpage at http://www.lunduniversity.lu.se/o.o.i.s?id=24914&Dnr=602507&Type=E
