Affiliation:
1. Department of Ecological Microbiology, University of Bayreuth, 95440 Bayreuth, Germany
2. Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
Abstract
ABSTRACT
Methanogenesis in wetlands is dependent on intermediary substrates derived from the degradation of biopolymers. Formate is one such substrate and is stimulatory to methanogenesis and acetogenesis in anoxic microcosms of soil from the fen Schlöppnerbrunnen. Formate dissimilation also yields CO
2
as a potential secondary substrate. The objective of this study was to resolve potential differences between anaerobic formate- and CO
2
-utilizing prokaryotes of this fen by stable isotope probing. Anoxic soil microcosms were pulsed daily with low concentrations of [
13
C]formate or
13
CO
2
(i.e., [
13
C]bicarbonate). Taxa were evaluated by assessment of 16S rRNA genes,
mcrA
(encoding the alpha-subunit of methyl-coenzyme M reductase), and
fhs
(encoding formyltetrahydrofolate synthetase). Methanogens, acetogens, and formate-hydrogen lyase-containing taxa appeared to compete for formate. Genes affiliated with
Methanocellaceae
,
Methanobacteriaceae
,
Acetobacteraceae
, and
Rhodospirillaceae
were
13
C enriched (i.e., labeled) in [
13
C]formate treatments, whereas genes affiliated with
Methanosarcinaceae
,
Conexibacteraceae
, and
Solirubrobacteraceae
were labeled in
13
CO
2
treatments. [
13
C]acetate was enriched in [
13
C]formate treatments, but labeling of known acetogenic taxa was not detected. However, several phylotypes were affiliated with acetogen-containing taxa (e.g.,
Sporomusa
).
Methanosaetaceae
-affiliated methanogens appeared to participate in the consumption of acetate. Twelve and 58 family-level archaeal and bacterial 16S rRNA phylotypes, respectively, were detected, approximately half of which had no isolated representatives.
Crenarchaeota
constituted half of the detected archaeal 16S rRNA phylotypes. The results highlight the unresolved microbial diversity of the fen Schlöppnerbrunnen, suggest that differing taxa competed for the same substrate, and indicate that
Methanocellaceae
,
Methanobacteriaceae
,
Methanosarcinaceae
, and
Methanosaetaceae
were linked to the production of methane, but they do not clearly resolve the taxa responsible for the apparent conversion of formate to acetate.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
59 articles.
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