The application of culture-dependent studies to quantify Fe-metabolizing microorganisms from the environment is a necessity, as there are so far no universal functional marker genes for application in culture-independent studies. Media composition can vary between studies, therefore, we determined the effects of three different growth media on the quantification (MPNs) and identity (via cloning and sequencing of dominant DGGE bands) of nitrate-reducing Fe(II)-oxidizers and lactate- or acetate-oxidizing Fe(III)-reducers from a lacustrine sediment: low sulphate freshwater medium (FWM), sterile filtered bicarbonate-buffered lake water (BLW) and a mixture of both (MIX). We consistently found fewer cells in the BLW than in the FWM and the MIX. The DGGE banding patterns of the microbial communities enriched in different media types clustered together according to the e− donor and acceptor couples and not according to the medium used. Thus, although the medium composition significantly influenced the quantification and thereby conclusions on the abundance and potential significance of the targeted group within the ecosystem, biodiversity assessments through enrichment cultures were less influenced by the medium, but instead were affected by the type and concentration of the e− donor/acceptor.
Bibliographical noteFunding Information:
This study was funded by a DFG grant to A.K. (KA1736/ 16-1), a Marie Curie ERG grant to C.S. (PERF04-GA-2008-239252) and a Landesgraduiertenfo€rderung fellowship to E.D.M. (Gz l 1.2_7631.2/Melton). This study was also supported by the European Research Council under the European Union’s Seventh Framework Program (FP/2007– 2013)/ERC Grant, Agreement n. 307320 – MICROFOX.
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- Lake Constance
- ferric iron
- ferrous iron
- microbial identity