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| Titel |
Increased bacterial growth efficiency with environmental variability: results from DOC degradation by bacteria in pure culture experiments |
| VerfasserIn |
M. Eichinger, R. Sempéré, G. Grégori, B. Charrière, J. C. Poggiale, D. Lefèvre |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 6 ; Nr. 7, no. 6 (2010-06-04), S.1861-1876 |
| Datensatznummer |
250004842
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| Publikation (Nr.) |
 copernicus.org/bg-7-1861-2010.pdf |
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| Zusammenfassung |
| This paper assesses how considering variation in DOC availability and cell
maintenance in bacterial models affects Bacterial Growth Efficiency (BGE)
estimations. For this purpose, we conducted two biodegradation experiments
simultaneously. In experiment one, a given amount of substrate was added to
the culture at the start of the experiment whilst in experiment two, the
same amount of substrate was added, but using periodic pulses over the time
course of the experiment. Three bacterial models, with different levels of
complexity, (the Monod, Marr-Pirt and the dynamic energy budget – DEB – models),
were used and calibrated using the above experiments. BGE has been
estimated using the experimental values obtained from discrete samples and
from model generated data. Cell maintenance was derived experimentally, from
respiration rate measurements. The results showed that the Monod model did
not reproduce the experimental data accurately, whereas the Marr-Pirt and
DEB models demonstrated a good level of reproducibility, probably because
cell maintenance was built into their formula. Whatever estimation method
was used, the BGE value was always higher in experiment two (the
periodically pulsed substrate) as compared to the initially
one-pulsed-substrate experiment. Moreover, BGE values estimated without
considering cell maintenance (Monod model and empirical formula) were always
smaller than BGE values obtained from models taking cell maintenance into
account. Since BGE is commonly estimated using constant experimental systems
and ignore maintenance, we conclude that these typical methods
underestimate BGE values. On a larger scale, and for biogeochemical cycles,
this would lead to the conclusion that, for a given DOC supply rate and a
given DOC consumption rate, these BGE estimation methods overestimate the
role of bacterioplankton as CO2 producers. |
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