In:
Applied and Environmental Microbiology, American Society for Microbiology, Vol. 71, No. 11 ( 2005-11), p. 6664-6672
Abstract:
Anaerobic or microaerophilic chemolithoautotrophic bacteria have been considered to be responsible for CO 2 dark fixation in different pelagic redoxclines worldwide, but their involvement in redox processes is still not fully resolved. We investigated the impact of 17 different electron donor/acceptor combinations in water of pelagic redoxclines from the central Baltic Sea on the stimulation of bacterial CO 2 dark fixation as well as on the development of chemolithoautotrophic populations. In situ, the highest CO 2 dark fixation rates, ranging from 0.7 to 1.4 μmol liter −1 day −1 , were measured directly below the redoxcline. In enrichment experiments, chemolithoautotrophic CO 2 dark fixation was maximally stimulated by the addition of thiosulfate, reaching values of up to 9.7 μmol liter −1 CO 2 day −1 . Chemolithoautotrophic nitrate reduction proved to be an important process, with rates of up to 33.5 μmol liter −1 NO 3 − day −1 . Reduction of Fe(III) or Mn(IV) was not detected; nevertheless, the presence of these potential electron acceptors influenced the development of stimulated microbial assemblages. Potential chemolithoautotrophic bacteria in the enrichment experiments were displayed on 16S ribosomal complementary DNA single-strand-conformation polymorphism fingerprints and identified by sequencing of excised bands. Sequences were closely related to chemolithoautotrophic Thiomicrospira psychrophila and Maorithyas hadalis gill symbiont (both Gammaproteobacteria ) and to an uncultured nitrate-reducing Helicobacteraceae bacterium ( Epsilonproteobacteria ). Our data indicate that this Helicobacteraceae bacterium could be of general importance or even a key organism for autotrophic nitrate reduction in pelagic redoxclines.
Type of Medium:
Online Resource
ISSN:
0099-2240
,
1098-5336
DOI:
10.1128/AEM.71.11.6664-6672.2005
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2005
detail.hit.zdb_id:
223011-2
detail.hit.zdb_id:
1478346-0
SSG:
12
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