Iron oxide deposits associated with the ectosymbiotic bacteria in the hydrothermal vent shrimp <i>Rimicaris exoculata</i>

Abstract

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 Mössbauer 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 threemineral 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.

The gill chamber epibiosis of deep‐sea shrimp Rimicaris exoculata: an in‐depth metagenomic investigation and discovery of Zetaproteobacteria

“…The Zetaproteobacteria were low in abundance and located on the surface of the branchiostegite membrane (inner face of the gill chamber) closely associated with the iron oxyhydroxide layer that accumulates between the shrimp's molts (Corbari et al, 2008a,b). This distinct association of close relatives of cultivated neutrophilic iron oxidizers and iron oxyhydroxides deposits in the gill chamber supports the hypothesis that R. exoculata associates with iron-oxidizing epibionts (Zbinden et al, 2004;2008;Corbari et al, 2008b;Guri et al, 2012). Zetaproteobacteria were found on all sampled R. exoculata individuals, indicating that Zetaproteobacteria might be regular members of the R. exoculata gill chamber community at the Rainbow hydrothermal vent site.…”

“…These data indicate that the epibionts might produce various extracellular structures as well as matrix polysaccharides allowing surface adhesion. The latter has been observed using TEM (Corbari et al, 2008b;Zbinden et al, 2008).…”

“…Shrimps from the Rainbow hydrothermal vent field of the MAR have a conspicuous rusty colour due to iron oxyhydroxide particle accumulation in their gill chambers. Close association of epibionts with these chemically inert iron oxyhydroxides led to the suggestion that some epibionts might oxidize iron (Zbinden et al, 2004;2008;Corbari et al, 2008b;Schmidt et al, 2008). However, no study has yet revealed the presence of iron-oxidizing bacteria in the gill chamber or provided evidence that previ-ously identified epibionts can oxidize iron.…”

Exploring the Effect of Operational Factors and Characterization Imperative to the Synthesis of Silver Nanoparticles

“…X-ray beam excitation is used in X-ray fluorescence (XRF) spectrometers. A detector is used to convert X-ray energy into voltage signals; this information is sent to a pulse processor, which measures the signals and passes them onto an analyzer for data display and analysis [66,67]. Most researchers utilize EDX for characterization of silver nanoparticles than XRF.…”

Upper littoral rhombognathines (Acari: Halacaridae) from Singapore: description of a new species

“…The fouling is most intense on adults but sparse on recently hatched protonymphs. Biofilms are commonly found on both littoral and deep-sea species (Gillan et al 2004;Corbari et al 2008;Caro et al 2012), and the integument of shallow brackish water as well as deep-sea hydrothermal vent halacarids may be covered with brown spots which most likely include iron hydroxide. Such films are often found on species of the genera Copidognathus and Halacarellus (Bartsch 1994(Bartsch , 2011.…”