Iron oxide deposits associated with the ectosymbiotic bacteria in the hydrothermal vent shrimp Rimicaris exoculata

Type Article
Date 2008-09
Language English
Author(s) Corbari L1, Cambon-Bonavita Marie-AnneORCID2, Long G3, Grandjean F4, Zbinden M5, Gaill F5, Compere P1
Affiliation(s) 1 : Univ Liege, Unite Morphol Ultrastruct & Cellule Appui Technol, Lab Morphol Fonct & Evolut, B-4000 Liege, Belgium.
2 : IFREMER, Ctr Brest, Lab Microbiol & Biotechnol Extremophiles, F-29280 Plouzane, France.
3 : Univ Missouri, Missouri Univ Sci & Technol, Dept Chem, Rolla, MO 65409 USA.
4 : Univ Liege, Dept Phys, B-4000 Sart Tilman Par Liege, Belgium.
5 : Univ Paris 06, CNRS, UMR Systemat Adaptat & Evolut 7138, F-75252 Paris 05, France.
Source Biogeosciences (1726-4170) (Biogeosciences), 2008-09 , Vol. 5 , N. 5 , P. 1295-1310
DOI 10.5194/bg-5-1295-2008
WOS© Times Cited 21
Keyword(s) mid atlantic ridge, deep sea, microbial communities, oxidizing bacteria, trophic ecology, ferrous ions, fe oxides, ferrihydrite, biomineralization, minerals
Abstract The Rimicaris exoculata shrimp is considered as a primary consumer that dominates the fauna of most Mid-Atlantic Ridge ( MAR) hydrothermal ecosystems. These shrimps harbour in their gill chambers an important ectosymbiotic community of chemoautotrophic bacteria associated with iron oxide deposits. The structure and elemental composition of the mineral concretions associated with these bacteria have been investigated by using LM, ESEM, TEM STEM and EDX microanalyses. The nature of the iron oxides in shrimps obtained from the Rainbow vent field has also been determined by Mossbauer spectroscopy. This multidisciplinary approach has revealed that the three layers of mineral crust in the Rimicaris exoculata shrimps consist of large concretions formed by aggregated nanoparticles of two-line ferrihydrite and include other minor elements as Si, Ca, Mg, S and P, probably present as silicates cations, sulphates or phosphates respectively that may contribute to stabilise the ferrihydrite form of iron oxides. TEM-observations on the bacteria have revealed their close interactions with these minerals. Abiotic and biotic precipitation could occur within the gill chamber of Rimicaris exoculata, suggesting the biologically-mediated formation of the iron oxide deposits. The difference of the bacterial density in the three-mineral crust layers could be correlated to the importance of the iron oxide concretions and suggest that the first mineral particles precipitates on the lower layer which could be considered as the most likely location of iron-oxidizing bacteria.
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