Strain-specific quorum-sensing responses determine virulence properties in Vibrio anguillarum.

Bacterial populations communicate using quorum-sensing (QS) molecules and switch on QS regulation to engage in coordinated behaviour such as biofilm formation or virulence. The marine fish pathogen Vibrio anguillarum harbours several QS systems, and our understanding of its QS regulation is still fragmentary. Here, we identify the VanT-QS regulon and explore the diversity and trajectory of traits under QS regulation in Vibrio anguillarum through comparative transcriptomics of two wildtype strains and their corresponding mutants artificially locked in QS-on (ΔvanO) or QS-off (ΔvanT) states.

Genomic Analysis of Provides Insight on Its Virulence Factors and Phylogeny and Highlights the Potential of Reverse Vaccinology in Aquaculture.

Pasteurellosis in farmed lumpsuckers, , has emerged as a serious disease in Norwegian aquaculture in recent years. Genomic characterization of the causative agent is essential in understanding the biology of the bacteria involved and in devising an efficient preventive strategy. The genomes of two clinical isolates were sequenced (≈2.

The Development of Bacteriophage Resistance in Depends on a Complex Metabolic Adaptation Strategy.

Lytic bacteriophages have been well documented to play a pivotal role in microbial ecology due to their complex interactions with bacterial species, especially in aquatic habitats. Although the use of phages as antimicrobial agents, known as phage therapy, in the aquatic environment has been increasing, recent research has revealed drawbacks due to the development of phage-resistant strains among Gram-negative species. Acquired phage resistance in marine has been proven to be a very complicated process utilizing biochemical, metabolic, and molecular adaptation strategies.

Large Phenotypic and Genetic Diversity of Prophages Induced from the Fish Pathogen .

is a marine pathogenic bacterium that causes vibriosis in fish and shellfish. Although prophage-like sequences have been predicted in strains, many are not characterized, and it is not known if they retain the functional capacity to form infectious particles that can infect and lysogenize other bacterial hosts. In this study, the genome sequences of 28 strains revealed 55 different prophage-related elements.

Complete Genome Sequence of Vibrio anguillarum Nontailed Bacteriophage NO16.

A rare nontailed virus designated NO16 was isolated against , a major aquaculture pathogen for both fish and shellfish. Here, we announce the 10,594-bp genome sequence of phage NO16 with a 23-gene content.

Characterization of a Highly Virulent Strain Isolated From Greek Aquaculture, and a Spontaneously Induced Prophage Therein.

-associated outbreaks are increasingly reported on both marine and freshwater aquaculture setups, accounting for severe financial and biomass losses. , and have been the traditional causative agents of edwardsiellosis in aquaculture, however, intensive studies due to the significance of the disease have just recently revealed two more species, and . Whole genome sequencing that was conducted on the strain EA011113, isolated from farmed after an edwardsiellosis outbreak in Greece, confirmed it as a new clinical strain of .

Phage defense mechanisms and their genomic and phenotypic implications in the fish pathogen Vibrio anguillarum.

Vibrio anguillarum is a marine bacterium that can cause vibriosis in many fish and shellfish species. Although phage therapy has been proposed as an alternative treatment, the defense mechanisms against phage infection in V. anguillarum and their impact on host function are not fully understood.

Widespread distribution of prophage-encoded virulence factors in marine Vibrio communities.

Prophages are known to encode important virulence factors in the human pathogen Vibrio cholerae. However, little is known about the occurrence and composition of prophage-encoded traits in environmental vibrios. A database of 5,674 prophage-like elements constructed from 1,874 Vibrio genome sequences, covering sixty-four species, revealed that prophage-like elements encoding possible properties such as virulence and antibiotic resistance are widely distributed among environmental vibrios, including strains classified as non-pathogenic.

Exploring the Effect of Phage Therapy in Preventing Infections in Cod and Turbot Larvae.

The aquaculture industry is suffering from losses associated with bacterial infections by opportunistic pathogens. is one of the most important pathogens, causing vibriosis in fish and shellfish cultures leading to high mortalities and economic losses. Bacterial resistance to antibiotics and inefficient vaccination at the larval stage of fish emphasizes the need for novel approaches, and phage therapy for controlling pathogens has gained interest in the past few years.

Bacteriophage Interactions with Marine Pathogenic Vibrios: Implications for Phage Therapy.

A global distribution in marine, brackish, and freshwater ecosystems, in combination with high abundances and biomass, make vibrios key players in aquatic environments, as well as important pathogens for humans and marine animals. Incidents of -associated diseases (vibriosis) in marine aquaculture are being increasingly reported on a global scale, due to the fast growth of the industry over the past few decades years. The administration of antibiotics has been the most commonly applied therapy used to control vibriosis outbreaks, giving rise to concerns about development and spreading of antibiotic-resistant bacteria in the environment.

Isolation and characterization of a N4-like lytic bacteriophage infecting Vibrio splendidus, a pathogen of fish and bivalves.

A novel virulent bacteriophage, vB_VspP_pVa5, infecting a strain of Vibrio splendidus was isolated from a sea-cage aquaculture farm in Greece, and characterized using microbiological methods and genomic analysis. Bacteriophage vB_VspP_pVa5 is a N4-like podovirus with an icosahedral head measuring 85 nm in length and a short non-contractile tail. The phage had a narrow host range infecting only the bacterial host, a latent period of 30 min and a burst size of 24 virions per infected bacterium.

Stumbling across the Same Phage: Comparative Genomics of Widespread Temperate Phages Infecting the Fish Pathogen Vibrio anguillarum.

Nineteen Vibrio anguillarum-specific temperate bacteriophages isolated across Europe and Chile from aquaculture and environmental sites were genome sequenced and analyzed for host range, morphology and life cycle characteristics. The phages were classified as Siphoviridae with genome sizes between 46,006 and 54,201 bp. All 19 phages showed high genetic similarity, and 13 phages were genetically identical.

Comparative Functional Genomic Analysis of Two Phages Reveals Complex Metabolic Interactions with the Host Cell.

Sequencing and annotation was performed for two large double stranded DNA bacteriophages, Grn1 and St2 of the family, considered to be of great interest for phage therapy against in aquaculture live feeds. In addition, phage-host metabolic interactions and exploitation was studied by transcript profiling of selected viral and host genes. Comparative genomic analysis with other large phages was also performed to establish the presence and location of homing endonucleases highlighting distinct features for both phages.

Global occurrence and heterogeneity of the Roseobacter-clade species Ruegeria mobilis.

Tropodithietic acid (TDA)-producing Ruegeria mobilis strains of the Roseobacter clade have primarily been isolated from marine aquaculture and have probiotic potential due to inhibition of fish pathogens. We hypothesized that TDA producers with additional novel features are present in the oceanic environment. We isolated 42 TDA-producing R.

Isolation and Characterization of Two Lytic Bacteriophages, φSt2 and φGrn1; Phage Therapy Application for Biological Control of Vibrio alginolyticus in Aquaculture Live Feeds.

Bacterial infections are a serious problem in aquaculture since they can result in massive mortalities in farmed fish and invertebrates. Vibriosis is one of the most common diseases in marine aquaculture hatcheries and its causative agents are bacteria of the genus Vibrio mostly entering larval rearing water through live feeds, such as Artemia and rotifers. The pathogenic Vibrio alginolyticus strain V1, isolated during a vibriosis outbreak in cultured seabream, Sparus aurata, was used as host to isolate and characterize the two novel bacteriophages φSt2 and φGrn1 for phage therapy application.

Effect of Bacteriophages on the Growth of Flavobacterium psychrophilum and Development of Phage-Resistant Strains.

The controlling effect of single and multiple phages on the density of Flavobacterium psychrophilum at different initial multiplicity of infection (MOI) was assessed in batch cultures to explore the potential for phage-based treatment of this important fish pathogen. A high initial phage concentration (MOI = 0.3-4) was crucial for efficient viral lysis, resulting in a 10(4)-10(5)-fold reduction of phage-sensitive cells (both single phages and phage cocktails), which was maintained throughout the incubation (>10 days).

Morphological characterisation and phylogenetic relationships of Zschokkella candia n. sp. from the gall-bladder of Sparisoma cretense (L.) (Perciformes: Scaridae) in the Sea of Crete off Greece.

A new myxosporean parasite, Zschokkella candia n. sp., from the gall-bladder of the wild parrotfish Sparisoma cretense (L.

Draft Genome Sequences of Vibrio alginolyticus Strains V1 and V2, Opportunistic Marine Pathogens.

We announce the draft genome sequences of Vibrio alginolyticus strains V1 and V2, isolated from juvenile Sparus aurata and Dentex dentex, respectively, during outbreaks of vibriosis. The genome sequences are 5,257,950 bp with a G+C content of 44.5% for V.

Enteromyxum leei infection in parrotfish, Sparisoma cretense: histopathological, morphological and molecular study.

Enteromyxum leei (Myxozoa) has been identified as the aetiological agent of morbidity and mortality in captive feral parrotfish, Sparisoma cretense held at the facilities of Cretaquarium, the public aquarium of the Hellenic Centre for Marine Research in Crete. The parasite caused substantial mortality to the parrotfish exceeding 60% over a period of 3.5 months.

Description and relationships of two novel species of Ceratomyxa Thelohan, 1892 infecting the gallbladders of Aulopiformes: Atlantic lizardfish Synodus saurus Linnaeus, 1758 and royal flagfin Aulopus filamentosus Bloch, 1792 from Cretan Sea, Greece.

Two members of Aulopiformes (grinners) were examined for myxosporean parasites in their gallbladders. Synodus saurus and Aulopus filamentosus from Cretan Sea, Greece were infected by Ceratomyxa parasites which are described in this paper. Both species of Ceratomyxa are new and referred for the first time as Ceratomyxa cretensis n.