Ecosystem functioning from a geomicrobiological perspective – a conceptual framework for biogeochemical iron cycling

Caroline Schmidt; Sebastian Behrens; Andreas Kappler

doi:10.1071/EN10040

RESEARCH ARTICLE

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Ecosystem functioning from a geomicrobiological perspective – a conceptual framework for biogeochemical iron cycling

Caroline Schmidt ^A , Sebastian Behrens ^A and Andreas Kappler ^A ^B

+ Author Affiliations

- Author Affiliations

^A Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Sigwartstrasse 10, D-72076 Tuebingen, Germany.

^B Corresponding author. Email: andreas.kappler@uni-tuebingen.de

Environmental Chemistry 7(5) 399-405 https://doi.org/10.1071/EN10040
Submitted: 22 April 2010 Accepted: 12 August 2010 Published: 13 October 2010

Environmental context. Microbial ecosystems are characterised by the interplay of various microorganisms with their biotic and abiotic environment. Biogeochemical niches host adapted microbial communities that are in constant competition for substrates and nutrients. Their natural distribution, interactions and responses to fluctuating environmental conditions are often impossible to simulate in laboratory studies. Using biogeochemical iron redox cycling as an example, we suggest the application of a conceptual framework to improve our understanding of the principal functioning of (geo)microbial ecosystems.

Abstract. Our knowledge on how microbial ecosystems function profits from the support of biogeochemical concepts which describe the cycling of elements through various geochemical gradients. Using the example of the iron cycle in freshwater sediments, we propose a theoretical framework that describes the dynamic interactions between chemical and microbial Fe^II oxidation and Fe^III reduction, their spatial location and how they are affected by changing environmental conditions. This contribution emphasises the complexity ecological research faces when dealing with heterogeneous and dynamic natural systems. Our concept aims to provide further insights into how flows of energy and matter are controlled during microbial and chemical Fe redox transformations and how various key variables, such as substrate availability and competition as well as thermodynamic and kinetic parameters, affect flow directions.

Additional keywords: bioenergetics, biogeochemistry, micro-ecology.

Acknowledgements

This work was supported by funding from the German Research Foundation (DFG; KA 1736/16-1) and a European Marie Curie Reintegration Grant (MC-ERG; PERG04-GA-2008-239252) to C. Schmidt, S. Behrens and A. Kappler and by funding from the Stifterverband der Wissenschaft to A. Kappler.

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