Cosmopolitan Distribution of Endozoicomonas-Like Organisms and Other Intracellular Microcolonies of Bacteria Causing Infection in Marine Mollusks

Type Article
Date 2020-10
Language English
Author(s) Cano Irene1, Ryder David1, Webb Steve C.2, Jones Brian J.3, Brosnahan Cara L.3, Carrasco Noelia4, Bodinier Barbara4, Furones Dolors4, Pretto Tobia5, Carella Francesca6, Chollet Bruno7, Arzul IsabelleORCID7, Cheslett Deborah8, Collins Evelyn9, Lohrmann Karin B.9, Valdivia Ana L.10, Ward Georgia10, Carballal María J.10, 11, 12, Villalba Antonio12, Marigómez Ionan13, Mortensen Stein14, Christison Kevin15, Kevin Wakeman C.16, Bustos Eduardo17, Christie Lyndsay1, Green Matthew1, Feist Stephen W.1
Affiliation(s) 1 : International Centre of Excellence for Aquatic Animal Health, Cefas Weymouth Laboratory, Weymouth, United Kingdom
2 : Cawthron Institute, Nelson, New Zealand
3 : Animal Health Laboratory, Ministry for Primary Industries, Upper Hutt, New Zealand
4 : Institut de Recerca i Tecnologia Agroalimentaries (IRTA), Sant Carles de la Ràpita, Tarragona, Spain
5 : Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Italy
6 : Department of Biology, University of Naples Federico II, Naples, Italy
7 : SG2M-LGPMM, Laboratoire De Génétique Et Pathologie Des Mollusques Marins, Ifremer, La Tremblade, France
8 : Marine Institute, Galway, Ireland
9 : Departamento de Biología Marina, Facultad de Ciencias del Mar, Universidad Católica del Norte, Centro Innovación Acuícola Aquapacífico, Coquimbo, Chile
10 : Life Sciences Department, Natural History Museum, London, United Kingdom
11 : Centro de Investigacións Mariñas, Consellería do Mar da Xunta de Galicia, Vilanova de Arousa, Spain
12 : Centro de Investigacións Mariñas, Consellería do Mar da Xunta de Galicia, Vilanova de Arousa, Spain
13 : Research Centre for Experimental Marine Biology and Biotechnology (PIE), University of the Basque Country (UPV/EHU), Plentzia, Spain
14 : Institute of Marine Research, Bergen, Norway
15 : Department of Environment, Forestry and Fisheries, Cape Town, South Africa
16 : Institute for International Collaboration, Hokkaido University, Sapporo, Japan
17 : Centro Acuícola Pesquero de Investigación Aplicada (CAPIA), Universidad Santo Tomás, Sede Puerto Montt, Chile
Source Frontiers In Microbiology (1664-302X) (Frontiers Media SA), 2020-10 , Vol. 11 , P. 577481 (22p.)
DOI 10.3389/fmicb.2020.577481
WOS© Times Cited 18
Keyword(s) mollusk, OTU, Endozoicomonas, Chlamydiae, Mycoplasma, Francisella, Lucinoma, Ridgeia

Intracellular microcolonies of bacteria (IMC), in some cases developing large extracellular cysts (bacterial aggregates), infecting primarily gill and digestive gland, have been historically reported in a wide diversity of economically important mollusk species worldwide, sometimes associated with severe lesions and mass mortality events. As an effort to characterize those organisms, traditionally named as Rickettsia or Chlamydia-like organisms, 1950 specimens comprising 22 mollusk species were collected over 10 countries and after histology examination, a selection of 99 samples involving 20 species were subjected to 16S rRNA gene amplicon sequencing. Phylogenetic analysis showed Endozoicomonadaceae sequences in all the mollusk species analyzed. Geographical differences in the distribution of Operational Taxonomic Units (OTUs) and a particular OTU associated with pathology in king scallop (OTU_2) were observed. The presence of Endozoicomonadaceae sequences in the IMC was visually confirmed by in situ hybridization (ISH) in eight selected samples. Sequencing data also indicated other symbiotic bacteria. Subsequent phylogenetic analysis of those OTUs revealed a novel microbial diversity associated with molluskan IMC infection distributed among different taxa, including the phylum Spirochetes, the families Anaplasmataceae and Simkaniaceae, the genera Mycoplasma and Francisella, and sulfur-oxidizing endosymbionts. Sequences like Francisella halioticida/philomiragia and Candidatus Brownia rhizoecola were also obtained, however, in the absence of ISH studies, the association between those organisms and the IMCs were not confirmed. The sequences identified in this study will allow for further molecular characterization of the microbial community associated with IMC infection in marine mollusks and their correlation with severity of the lesions to clarify their role as endosymbionts, commensals or true pathogens.

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Cano Irene, Ryder David, Webb Steve C., Jones Brian J., Brosnahan Cara L., Carrasco Noelia, Bodinier Barbara, Furones Dolors, Pretto Tobia, Carella Francesca, Chollet Bruno, Arzul Isabelle, Cheslett Deborah, Collins Evelyn, Lohrmann Karin B., Valdivia Ana L., Ward Georgia, Carballal María J., Villalba Antonio, Marigómez Ionan, Mortensen Stein, Christison Kevin, Kevin Wakeman C., Bustos Eduardo, Christie Lyndsay, Green Matthew, Feist Stephen W. (2020). Cosmopolitan Distribution of Endozoicomonas-Like Organisms and Other Intracellular Microcolonies of Bacteria Causing Infection in Marine Mollusks. Frontiers In Microbiology, 11, 577481 (22p.). Publisher's official version : , Open Access version :