April 21, 2020  |  

First report of isolation and complete genome of Vibrio rotiferianus strain SSVR1601 from cage-cultured black rockfish (Sebastes schlegelii) associated with skin ulcer.

Vibrio rotiferianus is an important marine pathogen of various aquatic organisms and can be found widely distributed in the marine environment. To further characterize this pathogen, the pathogenic properties and genome of V. rotiferianus SSVR1601 isolated from Sebastes schlegelii with skin ulcer were analysed. SSVR1601 was shown to be short rod-shaped cell with a single polar flagellum. Different degrees of pathological changes in fish kidney, intestine, gills and liver were observed after SSVR1601 challenge. The SSVR1601 genome consists of two chromosomes and two plasmids with a total of 5,717,113 bp, 42.04%-44.93% GC content, 5,269 predicted CDSs, 134 tRNAs and 40 rRNAs. The common virulence factors including OMPs, haemolysin, flagellin, DNase, entF, algU, tcpI, acfB and rfaD were found in strain SSVR1601. Furthermore, factors responsible for iron uptake (fur, fepC and ccmC) and types II, IV and VI secretion systems were detected, which are likely responsible for the pathogenicity of SSVR1601. The antimicrobial resistance genes, bacA, tet34 and norM, were detected based on Antibiotic Resistance Genes Database. The phylogenetic analysis revealed SSVR1601 to be most closely related to V. rotiferianus strains CAIM577 and B64D1. © 2019 John Wiley & Sons Ltd.

April 21, 2020  |  

Comparative genome analysis provides novel insight into the interaction of Aquimarina sp. AD1, BL5 and AD10 with their macroalgal host.

The Aquimarina genus is widely distributed throughout the marine environment, however little is understood regarding its ecological role, particularly when in association with eukaryotic hosts. Here, we examine the genomes of two opportunistic pathogens, Aquimarina sp. AD1 and BL5, and a non-pathogenic strain Aquimarina sp. AD10, that were isolated from diseased individuals of the red alga Delisea pulchra. Each strain encodes multiple genes for the degradation of marine carbohydrates and vitamin biosynthesis. These traits are hypothesised to promote nutrient exchange between the Aquimarina strains and their algal host, facilitating a close symbiotic relationship. Moreover, each strain harbours the necessary genes for the assembly of a Type 9 Secretion System (T9SS) and the associated gliding motility apparatus. In addition to these common features, pathogenic strains AD1 and BL5, encode genes for the production of flexirubin type pigments and a number of unique non-ribosomal peptide synthesis (NRPS) gene clusters, suggesting a role for these uncharacterised traits in virulence. This study provides valuable insight into the potential ecological role of Aquimarina in the marine environment and the complex factors driving pathogenesis and symbiosis in this genus.Copyright © 2019 Elsevier B.V. All rights reserved.

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