Gut dysbiosis induced by florfenicol increases susceptibility to Aeromonas hydrophila infection in Zebrafish Danio rerio after the recommended withdrawal period.

Objective: Florfenicol (FFC) is a broad-spectrum antibiotic approved by the U.S. Food and Drug Administration to treat both systemic and external bacterial infections in food fish.

Deciphering the Molecular Basis for Attenuation of Strain Fc1723 Used as Modified Live Vaccine against Columnaris Disease.

Vaccines are widely employed in aquaculture to prevent bacterial infections, but their use by the U.S. catfish industry is very limited.

Draft Genome Sequences of Cetobacterium somerae 2G Large and Two Novel Isolates from Intestines of Channel Catfish ().

We report the draft genome sequences of 2G Large and two isolates, 2A and 8H, which may represent novel species. The isolates were recovered from the intestines of catfish, and the genomes will assist in research to understand their potential use as probiotics in aquaculture.

Characterization of the normal equine conjunctival bacterial community using culture-independent methods.

Background: The equine conjunctival microbiota has often been reported to be dominated by Gram-positive species such as Staphylococcus sp., Bacillus sp., and Corynebacterium sp.

Transcriptome analysis of the fish pathogen Flavobacterium columnare in biofilm suggests calcium role in pathogenesis.

Background: Flavobacterium columnare is the causative agent of columnaris disease that affects cultured freshwater fishes worldwide. F. columnare easily colonizes surfaces by forming biofilm, which helps the pathogen resist antibiotic and disinfectant treatments.

Bacterial diversity and community structure of the intestinal microbiome of Channel Catfish (Ictalurus punctatus) during ontogenesis.

The acquisition of gut microbes does not occur randomly and is highly dependent on host factors, environmental cues, and self-assembly rules exerted by the microbes themselves. The main objective of this project was to characterize how the gut microbiome develops during the early life stages of Channel Catfish and to identify i) which bacteria are the main constituents of the gut microbiome at different ontogenesis stages, and ii) at which time point(s) the gut microbiome stabilizes. High-throughput Illumina Miseq DNA sequencing of the V4 domain of the 16S rRNA gene was used to assess the microbial community composition during the life stages of Channel Catfish along with water and feed samples.

More than just antibodies: Protective mechanisms of a mucosal vaccine against fish pathogen Flavobacterium columnare.

A recently developed attenuated vaccine for Flavobacterium columnare has been demonstrated to provide superior protection for channel catfish, Ictalurus punctatus, against genetically diverse columnaris isolates. We were interested in examining the mechanisms of this protection by comparing transcriptional responses to F. columnare challenge in vaccinated and unvaccinated juvenile catfish.

Effects of Desiccation Practices of Cultured Atlantic Oysters (Crassostrea virginica) on Vibrio spp. in Portersville Bay, Alabama, USA.

The expansion of off-bottom aquaculture to the Gulf of Mexico has raised public health concerns for human health officials. High temperatures in the Gulf of Mexico are associated with high levels of Vibrio parahaemolyticus and Vibrio vulnificus. Routine desiccation practices associated with off-bottom aquaculture expose oysters to ambient air, allowing Vibrio spp.

Biofilm Formation on Aquaculture Substrates by Selected Bacterial Fish Pathogens.

The objective of this study was to determine whether common bacterial catfish pathogens could attach and colonize surfaces commonly found in aquaculture facilities. In addition, we evaluated the role of calcium in biofilm formation. Attachment to polystyrene plates was used to quantify biofilm formation by five bacterial pathogens (i.

Microbiota of wild-caught Red Snapper Lutjanus campechanus.

Background: The microbiota plays an essential role in host health, particularly through competition with opportunistic pathogens. Changes in total bacterial load and microbiota structure can indicate early stages of disease, and information on the composition of bacterial communities is essential to understanding fish health. Although Red Snapper (Lutjanus campechanus) is an economically important species in recreational fisheries and a primary aquaculture candidate, no information is available on the microbial communities of this species.

Potassium permanganate elicits a shift of the external fish microbiome and increases host susceptibility to columnaris disease.

The external microbiome of fish is thought to benefit the host by hindering the invasion of opportunistic pathogens and/or stimulating the immune system. Disruption of those microbial communities could increase susceptibility to diseases. Traditional aquaculture practices include the use of potent surface-acting disinfectants such as potassium permanganate (PP, KMnO4) to treat external infections.

Comparison of DNA extraction protocols for the analysis of gut microbiota in fishes.

This study investigated the impacts of bacterial DNA extraction methodology on downstream analysis of fish gut microbiota. Feces and intestine samples were taken from three sympatric freshwater fish species with varying diets. Samples were processed immediately (approximately 4 h after capture; fresh), stored at -20 °C for 15 days or preserved in RNAlater® reagent for 15 days.

Community Structure of Skin Microbiome of Gulf Killifish, Fundulus grandis, Is Driven by Seasonality and Not Exposure to Oiled Sediments in a Louisiana Salt Marsh.

Mucus of fish skin harbors complex bacterial communities that likely contribute to fish homeostasis. When the equilibrium between the host and its external bacterial symbionts is disrupted, bacterial diversity decreases while opportunistic pathogen prevalence increases, making the onset of pathogenic bacterial infection more likely. Because of that relationship, documenting temporal and spatial microbial community changes may be predictive of fish health status.

Epidemiology of columnaris disease affecting fishes within the same watershed.

In the southeastern USA, columnaris disease (caused by Flavobacterium columnare) typically affects catfish raised in earthen ponds from early spring until late summer. Recently, unusually severe outbreaks of columnaris disease occurred at the E. W.

Predominant bacteria associated with red snapper from the Northern Gulf of Mexico.

Since the Deepwater Horizon oil spill in 2010, anecdotal observations of Red Snapper Lutjanus campechanus from the northern Gulf of Mexico exhibiting unusual external lesions have been reported. Two opportunistic bacterial fish pathogens, Vibrio vulnificus and Photobacterium damselae, were recovered from the fish and were deemed responsible for the abnormalities. However, the culturable microbiota of healthy Red Snapper has not yet been characterized.

New attenuated vaccine against columnaris disease in fish: choosing the right parental strain is critical for vaccine efficacy.

Flavobacterium columnare, the causative agent of columnaris disease, is a highly diverse species comprised by three genomovars. Genomovar II strains are more virulent toward catfishes than genomovar I isolates. The objective of this study was to compare the vaccine efficacy of avirulent mutants derived from genomovars I and II using a rifampicin-resistance strategy.

Biofilm formation by the fish pathogen Flavobacterium columnare: development and parameters affecting surface attachment.

Flavobacterium columnare is a bacterial fish pathogen that affects many freshwater species worldwide. The natural reservoir of this pathogen is unknown, but its resilience in closed aquaculture systems posits biofilm as the source of contagion for farmed fish. The objectives of this study were (i) to characterize the dynamics of biofilm formation and morphology under static and flow conditions and (ii) to evaluate the effects of temperature, pH, salinity, hardness, and carbohydrates on biofilm formation.

Diversity of the skin microbiota of fishes: evidence for host species specificity.

Skin microbiota of Gulf of Mexico fishes were investigated by ribosomal internal spacer analysis (RISA) and 16S rRNA gene sequencing. A total of 102 fish specimens representing six species (Mugil cephalus, Lutjanus campechanus, Cynoscion nebulosus, Cynoscion arenarius, Micropogonias undulatus, and Lagodon rhomboides) were sampled at regular intervals throughout a year. The skin microbiota from each individual fish was analyzed by RISA and produced complex profiles with 23 bands on average.

Effective reduction of Vibrio vulnificus in the Eastern oyster (Crassostrea virginica) using high salinity depuration.

Depuration under different salinities was used to reduce the human pathogen Vibrio vulnificus from Eastern oysters (Crassostrea virginica). Individual recirculating systems were used to test the efficacy of depuration at three salinities (15, 25, and 35 psu) in four independent trials during a 14 day period. Initial loads of V.

Adaptive response to starvation in the fish pathogen Flavobacterium columnare: cell viability and ultrastructural changes.

Background: The ecology of columnaris disease, caused by Flavobacterium columnare, is poorly understood despite the economic losses that this disease inflicts on aquaculture farms worldwide. Currently, the natural reservoir for this pathogen is unknown but limited data have shown its ability to survive in water for extended periods of time. The objective of this study was to describe the ultrastructural changes that F.

Prevalence and population structure of Vibrio vulnificus on fishes from the northern Gulf of Mexico.

The prevalence of Vibrio vulnificus on the external surfaces of fish from the northern Gulf of Mexico was determined in this study. A collection of 242 fish comprising 28 species was analyzed during the course of 12 sampling trips over a 16-month period. The prevalence of V.

Catfish hybrid Ictalurus punctatus × I. furcatus exhibits higher resistance to columnaris disease than the parental species.

We present experimental data on susceptibility to columnaris disease, caused by the bacterium Flavobacterium columnare, in hybrid catfish (female channel catfish Ictalurus punctatus × male blue catfish I. furcatus) (C×B). Under our experimental conditions, C×B hybrids were significantly more resistant to columnaris disease caused by the highly virulent strain of F.

Adhesion dynamics of Flavobacterium columnare to channel catfish Ictalurus punctatus and zebrafish Danio rerio after immersion challenge.

The adhesion dynamics of Flavobacterium columnare to fish tissues were evaluated in vivo by immersion challenge followed by bacterial plate count and confirmatory observations of gill-adhered bacterial cells using scanning electron microscopy. Adhesion of F. columnare genomovar I (ARS-1) and II (BGFS-27) strains to skin and gill of channel catfish Ictalurus punctactus and gill of zebrafish Danio rerio was compared.

Molecules infer origins of ectoparasite infrapopulations on tuna.

Infrapopulation genetic variation of the oioxenous, hermaphroditic flatworm Nasicola klawei (Monogenea: Capsalidae) infecting the nasal cavities of nine yellowfin tuna, Thunnus albacares, from the Gulf of Mexico was analyzed using the first internal transcribed spacer (ITS1) single strand conformation polymorphism (SSCP), ITS1 sequencing, and amplified fragment length polymorphism (AFLP). Of a total of 32 worms, six had unique ITS1-SSCP types and the rest was grouped by three types. Two worms of the same infrapopulation shared an ITS1-SSCP type in nine instances but no infrapopulation was monophyletic by ITS1-SSCP analysis.

A simplified and cost-effective enrichment protocol for the isolation of Campylobacter spp. from retail broiler meat without microaerobic incubation.

Background: To simplify the methodology for the isolation of Campylobacter spp. from retail broiler meat, we evaluated 108 samples (breasts and thighs) using an unpaired sample design. The enrichment broths were incubated under aerobic conditions (subsamples A) and for comparison under microaerobic conditions (subsamples M) as recommended by current reference protocols.