Journal article
Fate of Nitrate Acquired by the Tubeworm Riftia pachyptila
Applied and environmental microbiology, Vol.66(7), pp.2783-2790
07/2000
Handle:
https://hdl.handle.net/2376/109222
PMCID: PMC92073
PMID: 10877768
Abstract
The hydrothermal vent tubeworm
Riftia pachyptila
lacks a mouth and gut and lives in association with intracellular, sulfide-oxidizing chemoautotrophic bacteria. Growth of this tubeworm requires an exogenous source of nitrogen for biosynthesis, and, as determined in previous studies, environmental ammonia and free amino acids appear to be unlikely sources of nitrogen. Nitrate, however, is present in situ (K. Johnson, J. Childress, R. Hessler, C. Sakamoto-Arnold, and C. Beehler, Deep-Sea Res. 35:1723–1744, 1988), is taken up by the host, and can be chemically reduced by the symbionts (U. Hentschel and H. Felbeck, Nature 366:338–340, 1993). Here we report that at an in situ concentration of 40 μM, nitrate is acquired by
R. pachyptila
at a rate of 3.54 μmol g
−1
h
−1
, while elimination of nitrite and elimination of ammonia occur at much lower rates (0.017 and 0.21 μmol g
−1
h
−1
, respectively). We also observed reduction of nitrite (and accordingly nitrate) to ammonia in the trophosome tissue. When
R. pachyptila
tubeworms are exposed to constant in situ conditions for 60 h, there is a difference between the amount of nitrogen acquired via nitrate uptake and the amount of nitrogen lost via nitrite and ammonia elimination, which indicates that there is a nitrogen “sink.” Our results demonstrate that storage of nitrate does not account for the observed stoichiometric differences in the amounts of nitrogen. Nitrate uptake was not correlated with sulfide or inorganic carbon flux, suggesting that nitrate is probably not an important oxidant in metabolism of the symbionts. Accordingly, we describe a nitrogen flux model for this association, in which the product of symbiont nitrate reduction, ammonia, is the primary source of nitrogen for the host and the symbionts and fulfills the association's nitrogen needs via incorporation of ammonia into amino acids.
Metrics
7 Record Views
Details
- Title
- Fate of Nitrate Acquired by the Tubeworm Riftia pachyptila
- Creators
- Peter R Girguis - Marine Science Institute, University of California at Santa Barbara, Santa Barbara, California 93106Raymond W Lee - Marine Science Institute, University of California at Santa Barbara, Santa Barbara, California 93106Nicole Desaulniers - Marine Science Institute, University of California at Santa Barbara, Santa Barbara, California 93106James J Childress - Marine Science Institute, University of California at Santa Barbara, Santa Barbara, California 93106Mark Pospesel - Marine Science Institute, University of California at Santa Barbara, Santa Barbara, California 93106Horst Felbeck - Marine Science Institute, University of California at Santa Barbara, Santa Barbara, California 93106Franck Zal - Marine Science Institute, University of California at Santa Barbara, Santa Barbara, California 93106
- Publication Details
- Applied and environmental microbiology, Vol.66(7), pp.2783-2790
- Publisher
- American Society for Microbiology
- Identifiers
- 99900547276001842
- Language
- English
- Resource Type
- Journal article