• Global Warming:

    the threat of a permafrost Carbon – climate feedback

  • We develop and improve

    stable isotopes techniques for ecological applications

  • Plants, fungi and bacteria interact

    at the root-soil interface

  • Probing the future:

    Climate Change experiments

  • Soil is fundamental to human life

  • Tropical rainforests

    hold the key to global net primary productivity

TER News

Latest publications

Flux Analysis of Free Amino Sugars and Amino Acids in Soils by Isotope Tracing with a Novel Liquid Chromatography/High Resolution Mass Spectrometry Platform

Soil fluxomics analysis can provide pivotal information for understanding soil biochemical pathways and their regulation, but direct measurement methods are rare. Here, we describe an approach to measure soil extracellular metabolite (amino sugar and amino acid) concentrations and fluxes based on a 15N isotope pool dilution technique via liquid chromatography and high-resolution mass spectrometry. We produced commercially unavailable 15N and 13C labeled amino sugars and amino acids by hydrolyzing peptidoglycan isolated from isotopically labeled bacterial biomass and used them as tracers (15N) and internal standards (13C). High-resolution (Orbitrap Exactive) MS with a resolution of 50 000 allowed us to separate different stable isotope labeled analogues across a large range of metabolites. The utilization of 13C internal standards greatly improved the accuracy and reliability of absolute quantification. We successfully applied this method to two types of soils and quantified the extracellular gross fluxes of 2 amino sugars, 18 amino acids, and 4 amino acid enantiomers. Compared to the influx and efflux rates of most amino acids, similar ones were found for glucosamine, indicating that this amino sugar is released through peptidoglycan and chitin decomposition and serves as an important nitrogen source for soil microorganisms. d-Alanine and d-glutamic acid derived from peptidoglycan decomposition exhibited similar turnover rates as their l-enantiomers. This novel approach offers new strategies to advance our understanding of the production and transformation pathways of soil organic N metabolites, including the unknown contributions of peptidoglycan and chitin decomposition to soil organic N cycling.

Hu Y, Zheng Q, Wanek W
2017 - analytical chemistry, 17: 9192-9200

Increased temperature causes different carbon and nitrogen processing patterns in two common intertidal foraminifera (Ammonia tepida and Haynesina germanica)

Benthic foraminifera are highly abundant heterotrophic protists in marine sediments, but future environmental changes will challenge the tolerance limits of intertidal species. Metabolic rates and physiological processes in foraminifera are strongly dependent on environmental temperatures. Temperature-related stress could therefore impact foraminiferal food source processing efficiency and might result in altered nutrient fluxes through the intertidal food web. In this study, we performed a laboratory feeding experiment on Ammonia tepida and Haynesina germanica, two dominant foraminiferal species of the German Wadden Sea/Friedrichskoog, to test the effect of temperature on phytodetritus retention. The specimens were fed with C-13 and N-15 labelled freeze-dried Dunaliella tertiolecta (green algae) at the start of the experiment and were incubated at 20, 25 and 30 degrees C respectively. Dual labelling was applied to observe potential temperature effects on the relation of phytodetrital carbon and nitrogen retention. Samples were taken over a period of 2 weeks. Foraminiferal cytoplasm was isotopically analysed to investigate differences in carbon and nitrogen uptake derived from the food source. Both species showed a positive response to the provided food source, but carbon uptake rates of A. tepida were 10-fold higher compared to those of H. germanica. Increased temperatures had a far stronger impact on the carbon uptake of H. germanica than on A. tepida. A distinct increase in the levels of phytodetrital-derived nitrogen (compared to more steady carbon levels) could be observed over the course of the experiment in both species. The results suggest that higher temperatures have a significant negative effect on the carbon exploitation of H. germanica. For A. tepida, higher carbon uptake rates and the enhanced tolerance range for higher temperatures could outline an advantage in warmer periods if the main food source consists of chlorophyte phytodetritus. These conditions are likely to impact nutrient fluxes in A. tepida/H. germanica associations.

Wukovits J, Enge AJ, Wanek W, Watzka M, Heinz P
2017 - Biogeosciences, 11: 2815-2829

Optimal metabolic regulation along resource stoichiometry gradients

Most heterotrophic organisms feed on substrates that are poor in nutrients compared to their
demand, leading to elemental imbalances that may constrain their growth and function. Flexible
carbon (C)-use efficiency (CUE, C used for growth over C taken up) can represent a strategy to
reduce elemental imbalances. Here, we argue that metabolic regulation has evolved to maximise
the organism growth rate along gradients of nutrient availability and translated this assumption
into an optimality model that links CUE to substrate and organism stoichiometry. The optimal
CUE is predicted to decrease with increasing substrate C-to-nutrient ratio, and increase with
nutrient amendment. These predictions are generally confirmed by empirical evidence from a new
database of c. 2200 CUE estimates, lending support to the hypothesis that CUE is optimised
across levels of organisation (microorganisms and animals), in aquatic and terrestrial systems, and
when considering nitrogen or phosphorus as limiting nutrients.

Manzoni S, Capek P, Mooshammer M, Lindahl BD, Richter A, Santruckova H
2017 - Ecology Letters, 20: 1182-1191

Lecture series

Microbial function in relation to plant productivity and root exudation in contrasting tundra communities

Konstantin GAVAZOV
Climate Impacts Research Centre (CIRC), Umeå University, Abisko, Sweden
14:00 h
Seminar Room 'Konferenzraum Ökologie' UZA 1, Althanstr. 14, 1090 Wien

LC-MS Approaches in Metabolomics

Gunda Köllensperger, Prof.
University of Vienna, Department of Analytical Chemistry
11:15 h
Seminar Room Microbial Ecology, UZA 1, room no 2.309

Arbuscular mycorrhizas and organic nitrogen in soil – and the other microbes involved

Jan Jasna
Institute of Microbiology, Academy of Sciences of the Czech Republic
16:00 h
Friedrich-Becke Seminar Room, UZA 2 (Geozentrum), Althanstr. 14, 1090 Wien