Research
Theme 1 & 2
www.darwincenter.nl
Program 1030

The role of microbial activity in iron-deposition in wetland ecosystems
Program coordinator(s): Prof. dr. H. J. Laanbroek
Theme(s): 1
Funding date: 11-jan-06

Abstract
Wetland plants are adapted to anoxia as it prevails under waterlogged conditions. By the formation of aerenchyma these plants are able to maintain oxic conditions in their root system as well as in some parts of in the so-called rhizosphere outside the roots. By doing so, plants favour chemical and microbial oxidation processes and hence interfere with all kind of geochemical cycles in the otherwise anoxic environment. The presence of plaques of oxidised iron around the roots of wetland plants indicate an active iron cycling in the rhizosphere. Hardly anything is known about the biotic and abiotic constraints of this microbial activity under natural conditions. The nature of the oxidised rhizosphere is very complex with respect the fluxes of oxidised and reduced compounds. Therefore unravelling the role of microbial activity in iron deposition requires a combination of field and model studies, as well as the collaboration between microbial ecologists and biogeochemists. The program aims at deepening our knowledge on the role of bacteria in wetland ecosystems by using a number of sophisticated tools such as molecular biology, dynamic model systems and different models to describe the behaviour of iron deposition.

This program contains the following projects:
1031: Ecology of iron-oxidizing bacteria in wetland environments
1032: Microbial iron oxidation under oxygen-limited conditions: Rates, competition and spatial patterns in the rhizosphere of wetland plants

Publications
Wang, J., Muyzer, G., Bodelier, P.L.E., Laanbroek, H.J. (2009). Diversity of iron oxidizers in wetland soils revealed by novel 16S rRNA primers targeting Gallionella-related bacteria . ISME Journal3 (6): 715-725.
Darwin Center authors: Bodelier P. L. E., Laanbroek H. J., Wang J.

Wang, J., Vollrath, S., Behrends, T., Bodelier, P.L.E., Muyzer, G., Meima-Franke, M., Oudsten, F.D., Van Cappellen, P., Laanbroek, H.J. (2011). Distribution and diversity of Gallionella-like neutrophilic iron oxidizers in a tidal freshwater marsh . Applied and Environmental MicrobiologyVolume 77, Issue 7: 2337-2344.
Darwin Center authors: Behrends T., Bodelier P. L. E., Laanbroek H. J., Van Cappellen P., Vollrath S., Wang J.

Juanjuan Wang (2011). Ecology of neutrophilic iron-oxidizing bacteria in wetland soils. February 2011.
Darwin Center authors: Wang J.

Suzann Vollrath (2012). Microbial Fe(II) oxidation at circumneutral pH: Reaction kinetics, mineral products, and distribution of neutrophilic iron oxidizers in wetland soils.. January 2012.
Darwin Center authors: Vollrath S.

Susann Vollrath, Thilo Behrends & Philippe Van Cappellen (2012). Oxygen Dependency of Neutrophilic Fe(II) Oxidation by Leptothrix Differs from Abiotic Reaction . Geomicrobiology Journal26-6: 550-560.
Darwin Center authors: Behrends T., Vollrath S.

Wang J, Krause S, Muyzer G, Meima-Franke M, Laanbroek HJ, Bodelier PLE (2012). Spatial patterns of iron- and methane-oxidizing bacterial communities an in an irregularly flooded, riparian wetland. Frontiers in Microbiology3:
Darwin Center authors: Bodelier P. L. E., Laanbroek H. J., Wang J.