Morphology of a ferric iron-encrusted biofilm forming on the shell of a burrowing bivalve (Mollusca)

Abstract

The shell of the bivalve Montacuta ferruginosa is usually covered with a rust-coloured and ferric iron-encrusted biofilm. The latter is a structured microbial mat with 3 separate layers. The outer layer is essentially microbial (f~lamentous bacteria and protozoa). The intermediary layer is both microblal and mineral (heavily fernc iron-encrusted filamentous bacteria and protozoa) The inner layer is essentially mineral (ferric iron deposits) and generally devoid of living microorgan~sms. The most abundant microorganisms in the biofilm are filamentous bacteria related to Beggiatoaceae. The genesis of this mineral-microbial mat could be partly due to a sequence of processes: (1) ferric iron deposition within bacterial sheaths in the outer layer; (2) the release and accumulation of heavily ferric ironencrusted sheaths after lysis of the bacteria in the intermediary layer; (3) degradation of bacterial sheaths and accumulation of ferric iron minerals in the inner layer.

Differential Growth of and Nanoscale TiO 2 Accumulation in Tetrahymena thermophila by Direct Feeding versus Trophic Transfer from Pseudomonas aeruginosa

“…With other nontoxic nanoscale metals, biomagnification does not occur since the predator-prey interactions facilitate metal recycling. For example, many iron-encrusted microbial communities are continually being grazed on by protozoa (43,44) and the iron is ultimately utilized in protozoan and bacterial processes (45,46) as an alternate Fe source that increases productivity and nitrogen uptake in food webs (47)(48)(49). Protozoa also engulf manganese-encrusted bacteria, which contributes to the geochemical cycling of Mn during normal protozoan bacterial digestion (50).…”

Epibiotic bacterial community of Sphaeroma serratum (Crustacea, Isopoda): relationship with molt status

“…In the literature, several morphotypes of filamentous bacteria are frequently encountered on the same host species. Although morphology alone is of little use in identifying bacteria, some were related to sulfur-oxidizing bacteria such as Thiotrix (Gillan & De Ridder 1997, Gillan & Dubilier 2004 or Leucothrix , Petersen et al 2010 according to morphology and molecular techniques. In the bacterial community hosted in the branchial chamber of Rimicaris (Crustaceae), 3 different morphotypes were initially described (2 filamentous bacteria and one rod-shaped bacterium); they were affili ated with 3 different bacterial phylogenetic groups: the ε-Proteobacteria (Polz & Cavanaugh 1995), the γ-Proteobacteria (Petersen et al 2010) and the δ-Proteobacteria (Hügler et al 2011).…”

“…(Katz et al 2006). Moreover, some studies have revealed the presence of epibiotic bacteria in association with invertebrates living at shallow depth in the seashore environment, as described for molluscs (Gillan & De Ridder 1997, Gillan et al 1998, ascidians (Tait et al 2007) or echinoderms (Brigmon & De Ridder 1998). For Crustacea, a small amphipod, Urothoe posedonis, living in marine sediment or as a commensal in the burrows of various invertebrates , Lackschewitz & Reise 1998) was described to be associated with an iron-encrusted epibiotic microbial community .…”

Novel Epibiotic Thiothrix Bacterium on a Marine Amphipod

“…Although other morphotypes of epibiotic bacteria are known to occur on U. poseidonis (10), only the Thiothrix-like filaments hybridized to the UP23b probe. Epibiotic filamentous bacteria have also been described from the shells of the bivalve Montacuta ferruginosa, another invertebrate living in the burrow of E. cordatum (9,11), and have been reported to occur in the nodules of the digestive tube of E. cordatum (2,26). These filamentous bacteria did not hybridize with the UP23b probe.…”

“…can also occur as epibionts on aquatic invertebrates such as mayfly larvae (17), tadpoles (7), hydrothermal vent organisms (14), intertidal sediment dwellers (9,22), and the sea urchin Echinocardium cordatum (2,26). However, these Thiothrix-like bacteria were mainly identified on the basis of their morphology (2,7,9,17) or by using immunological methods (2). It is now known that morphology alone is of little use in identifying Thiothrix spp.…”