New insights into the haemo‐ and coelo‐microbiota with antimicrobial activities from Echinodermata and Mollusca

Abstract

Aims: The aim of this study was to investigate the diversity of bacteria with antimicrobial activity present in the coelomic fluid and haemolymph of wild and healthy echinodermata and mollusca. Methods and Results: Collection expeditions of healthy marine molluscs and echinoderms were conducted in the Glenan archipelago in spring 2014. Members of the culturable microbiota present in the haemolymph, (haemomicrobiota) of Haliotis tuberculata (gastropoda, abalone) and Mytilus edulis (bivalvia, mussel), as well as in the coelomic fluid (coelo-microbiota) of Echinus esculentus (echinoidea, sea urchin) and Holothuria forskali (Holothuroidea, holothurian) were screened for antimicrobial activity, and further identified using 16S rRNA sequencing. Except for E. esculentus, culturable bacteria in the internal fluids of all studied organisms (mussel, abalone and holothurian) were more abundant than in seawater. The haemo-and coelo-microbiota with antimicrobial activity differed significantly between host species, in terms of abundance and diversity. Indeed, higher numbers were isolated from mussel than from abalone haemolymph. Moreover, in mussels and holothurians, bacteria with antimicrobial activities were predominantly Vibrio spp. (respectively 55 and 45%), while Pseudoalteromonas spp. were the most abundant (50%) in abalone haemolymph. Nevertheless, the activity spectra of these bacteria mainly included marine pathogens affiliated to the Vibrio genus. Conclusion: The haemo-and coelo-microbiota with antimicrobial activities were significantly related to their host species and differed in terms of abundance and diversity. These bacteria may play a key role in host homeostasis against pathogens. Significance and Impact of the Study: This study brings new knowledge on the diversity of bacteria present in the internal fluids of two marine molluscs and two echinoderms and their antimicrobial activities towards marine pathogens. Rosenberg and Rosenberg 2008). Despite still being a matter of discussion (Theis et al. 2016), advances in next generation DNA sequencing (NGS) and the development of metabolomics have shed light on the crucial role of the microbiota in host homeostasis (Heindl et al. 2010; Flemer et al. 2012).

The marine intertidal zone shapes oyster and clam digestive bacterial microbiota

“…Host-associated microbiota consist of more or less complex communities of microorganisms, some of which are more adapted to their host, others generalist, or transient, representing a wide range of potential contributions (Shapira 2017). It is well known that bivalves harbor their own microbiota (as for other organisms), whose characteristics and functions are still poorly understood, but cannot be ignored (Desriac et al 2014;Offret et al 2019).…”

The hemolymph of Biomphalaria snail vectors of schistosomiasis supports a diverse microbiome

“…Therefore the hemolymph microbiome is likely to be most relevant for understanding interactions between snails, bacteria and developing schistosomes. Furthermore, evidence from other mollusk species provide a precedent for investigating the Biomphalaria microbiome: hemolymphs from several fresh and seawater mollusks and crustaceans are known to harbor specific microbiomes (Antunes et al ., 2010; Desriac et al ., 2014; Vezzulli et al ., 2018; Zhang et al ., 2018; Offret et al ., 2019; Musella et al ., 2020; Table 1) that can be modified by environmental stress (Lokmer and Mathias Wegner, 2015), pollutants (Leite et al ., 2017; Auguste et al ., 2019) or pathogens (Vezzulli et al ., 2013; Lokmer and Mathias Wegner, 2015).…”

The role of diversity in mediating microbiota structural and functional responses in two sympatric species of abalone under stressed withering syndrome conditions

“…Indeed, resident microbiotas may outcompete pathogens for space, metabolites, and nutrients [23,56] or inhibit and even kill pathogens via metabolic byproducts (e.g., bacteriocins, acids, and peptides) [57,58]. This may be particularly important in abalone, as higher interspeci c microbiota diversity is generally explained by an increase in Alphaand Gammaproteobacteria [6,33,59], both of which represent the main taxonomic groups that produce antimicrobial compounds in abalone species [60,61]. Thus, we posit that the lower susceptibility to WS observed in HC may be explained by both a high prevalence of Alphaand Gammaproteobacteria [33] and the production of associated byproducts.…”