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| Titel |
Exploring Microbial Iron Oxidation in Wetland Soils |
| VerfasserIn |
J. Wang, G. Muyzer, P. L. E. Bodelier, F. den Oudsten, H. J. Laanbroek |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026796
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| Zusammenfassung |
| Iron is one of the most abundant elements on earth and is essential for life. Because of its
importance, iron cycling and its interaction with other chemical and microbial processes has
been the focus of many studies. Iron-oxidizing bacteria (FeOB) have been detected in a wide
variety of environments. Among those is the rhizosphere of wetland plants roots which
release oxygen into the soil creating suboxic conditions required by these organisms. It has
been reported that in these rhizosphere microbial iron oxidation proceeds up to four orders of
magnitude faster than strictly abiotic oxidation. On the roots of these wetland plants iron
plaques are formed by microbial iron oxidation which are involved in the sequestering of
heavy metals as well organic pollutants, which of great environmental significance.Despite
their important role being catalysts of iron-cycling in wetland environments, little is
known about the diversity and distribution of iron-oxidizing bacteria in various
environments.
This study aimed at developing a PCR-DGGE assay enabling the detection of iron
oxidizers in wetland habitats. Gradient tubes were used to enrich iron-oxidizing bacteria.
From these enrichments, a clone library was established based on the almost complete 16s
rRNA gene using the universal bacterial primers 27f and 1492r. This clone library consisted
of mainly α- and β-Proteobacteria, among which two major clusters were closely related to
Gallionella spp. Specific probes and primers were developed on the basis of this 16S rRNA
gene clone library. The newly designed Gallionella-specific 16S rRNA gene primer
set 122f/998r was applied to community DNA obtained from three contrasting
wetland environments, and the PCR products were used in denaturing gradient
gel electrophoresis (DGGE) analysis. A second 16S rRNA gene clone library was
constructed using the PCR products from one of our sampling sites amplified with the
newly developed primer set 122f/998r. The cloned 16S rRNA gene sequences all
represented novel culturable iron oxidizers most closely related to Gallionella spp.
Based on their nucleotide sequences four groups could be identified, which were
comparable to the DGGE banding pattern obtained before with the gradient tubes
enrichments.
The above mentioned nested PCR-DGGE method was used to study the distribution and
community composition of Gallionella-like iron-oxidizing bacteria under the influence of
plants species, soil depth, as well as season. Soil samples from Appels, Belgium,
an intertidal, freshwater marsh known to hold intensive iron cycling, were taken
from 5 different vegetation types in April, July and October 2007. Soil cores were
sliced at 1-cm intervals and subjected to chemical and molecular analyses. The
DGGE patterns showed that the community of iron-oxidizing bacteria differed with
vegetation type, and sediment depth. Samples taken in autumn held lower diversity
in Gallionella-related iron oxidizers than those sampled in spring and summer. |
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