title: Environmental marine pathogen isolation using mesocosm culture of sharpsnout seabream: striking genomic and morphological features of novel Endozoicomonas sp.
abstract: Aquaculture is a burgeoning industry, requiring diversification into new farmed species, which are often at risk from infectious disease. We used a mesocosm technique to investigate the susceptibility of sharpsnout seabream (Diplodus puntazzo) larvae to potential environmental pathogens in seawater compared to control borehole water. Fish exposed to seawater succumbed to epitheliocystis from 21 days post hatching, causing mortality in a quarter of the hosts. The pathogen responsible was not chlamydial, as is often found in epitheliocystis, but a novel species of the γ-proteobacterial genus Endozoicomonas. Detailed characterisation of this pathogen within the infectious lesions using high resolution fluorescent and electron microscopy showed densely packed rod shaped bacteria. A draft genome sequence of this uncultured bacterium was obtained from preserved material. Comparison with the genome of the Endozoicomonas elysicola type strain shows that the genome of Ca. Endozoicomonas cretensis is undergoing decay through loss of functional genes and insertion sequence expansion, often indicative of adaptation to a new niche or restriction to an alternative lifestyle. These results demonstrate the advantage of mesocosm studies for investigating the effect of environmental bacteria on susceptible hosts and provide an important insight into the genome dynamics of a novel fish pathogen.
authors.affiliation: Institute of Marine Biology, Biotechnology and Aquaculture, Hellenic Center for Marine Research, Heraklion, Crete, Greece.
authors.forename: Pantelis
authors.initials: P
authors.lastname: Katharios
authors.affiliation: Functional Genomics Center Zürich, University of Zürich, Switzerland.|Institute for Veterinary Pathology, Vetsuisse Faculty, University of Zürich, Switzerland.
authors.forename: Helena M B
authors.initials: HM
authors.lastname: Seth-Smith
authors.affiliation: Institute for Veterinary Pathology, Vetsuisse Faculty, University of Zürich, Switzerland.
authors.forename: Alexander
authors.initials: A
authors.lastname: Fehr
authors.affiliation: Center for Microscopy and Image Analysis, University of Zürich, Switzerland.
authors.forename: José M
authors.initials: JM
authors.lastname: Mateos
authors.affiliation: Functional Genomics Center Zürich, University of Zürich, Switzerland.
authors.forename: Weihong
authors.initials: W
authors.lastname: Qi
authors.affiliation: Institute for Veterinary Pathology, Vetsuisse Faculty, University of Zürich, Switzerland.
authors.forename: Denis
authors.initials: D
authors.lastname: Richter
authors.affiliation: Institute for Veterinary Pathology, Vetsuisse Faculty, University of Zürich, Switzerland.
authors.forename: Lisbeth
authors.initials: L
authors.lastname: Nufer
authors.affiliation: Institute for Veterinary Pathology, Vetsuisse Faculty, University of Zürich, Switzerland.
authors.forename: Maja
authors.initials: M
authors.lastname: Ruetten
authors.affiliation: Institute for Veterinary Pathology, Vetsuisse Faculty, University of Zürich, Switzerland.|Center for Fish and Wild Animal Medicine, Vetsuisse Faculty, University of Bern, Switzerland.
authors.forename: Maricruz
authors.initials: M
authors.lastname: Guevara Soto
authors.affiliation: Center for Microscopy and Image Analysis, University of Zürich, Switzerland.
authors.forename: Urs
authors.initials: U
authors.lastname: Ziegler
authors.affiliation: The Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom.
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Thomson
authors.affiliation: Functional Genomics Center Zürich, University of Zürich, Switzerland.
authors.forename: Ralph
authors.initials: R
authors.lastname: Schlapbach
authors.affiliation: Institute for Veterinary Pathology, Vetsuisse Faculty, University of Zürich, Switzerland.
authors.forename: Lloyd
authors.initials: L
authors.lastname: Vaughan
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004783:Environmental Microbiology; D020563:Gammaproteobacteria / Q000166:cytology* / Q000302:isolation & purification*; D023281:Genomics / Q000379:methods*; D017404:In Situ Hybridization, Fluorescence; D007814:Larva / Q000648:ultrastructure; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D021541:Sea Bream / Q000382:microbiology*; D012623:Seawater / Q000382:microbiology*; D017422:Sequence Analysis, DNA
chemical_list: D012336:RNA, Ribosomal, 16S