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Vibriosis outbreaks in aquaculture: addressing environmental and public health concerns and preventive therapies using gilthead seabream farming as a model system

Publication . Sanches-Fernandes, Gracinda M. M.; Sá-Correia, Isabel; Da Silva Costa, Rodrigo

Bacterial and viral diseases in aquaculture result in severe production and economic losses. Among pathogenic bacteria, species belonging to the Vibrio genus are one of the most common and widespread disease-causing agents. Vibrio infections play a leading role in constraining the sustainable growth of the aquaculture sector worldwide and, consequently, are the target of manifold disease prevention strategies. During the early, larval stages of development, Vibrio species are a common cause of high mortality rates in reared fish and shellfish, circumstances under which the host organisms might be highly susceptible to disease preventive or treatment strategies such as vaccines and antibiotics use, respectively. Regardless of host developmental stage, Vibrio infections may occur suddenly and can lead to the loss of the entire population reared in a given aquaculture system. Furthermore, the frequency of Vibrio-associated diseases in humans is increasing globally and has been linked to anthropic activities, in particular human-driven climate change and intensive livestock production. In this context, here we cover the current knowledge of Vibrio infections in fish aquaculture, with a focus on the model species gilthead seabream (Sparus aurata), a highly valuable reared fish in the mediterranean climatic zone. Molecular methods currently used for fast detection and identification of Vibrio pathogens and their antibiotic resistance profiles are addressed. Targeted therapeutic approaches are critically examined. They include vaccination, phage therapy and probiotics supplementation, which bear promise in supressing vibriosis in land-based fish rearing and in mitigating possible threats to human health and the environment. This literature review suggests that antibiotic resistance is increasing among Vibrio species, with the use of probiotics constituting a promising, sustainable approach to prevent Vibrio infections in aquaculture.

2022-07Journal article

Open access

Draft genome sequence of vibrio jasicida 20LP, an opportunistic bacterium isolated from fish larvae

Publication . Sanches-Fernandes, Gracinda M. M.; Califano, Gianmaria; Keller-Costa, Tina; Castanho, Sara; Soares, Florbela; Ribeiro, Laura; Pousão-Ferreira, Pedro; Mata, Leonardo; Costa, Rodrigo

We present the genome sequence of Vibrio jasicida 20LP, a bacterial strain retrieved from larvae of gilthead seabream (Sparus aurata), a highly valuable, model fish species in land-based aquaculture. Annotation of the V. jasicida 20LP genome reveals multiple genomic features potentially underpinning opportunistic associations with diverse marine animals.

2021-11Journal article

Open access

Effects of live feed manipulation with algal‐derived antimicrobial metabolites on fish larvae microbiome assembly: a molecular‐based assessment

Publication . Sanches‐Fernandes, Gracinda M. M.; Califano, Gianmaria; Castanho, Sara; Soares, Florbela; Ribeiro, Laura; Pousão‐Ferreira, Pedro; Mata, Leonardo; Costa, Rodrigo

Opportunistic microorganisms acquired through rearing water or live feed ingestion are believed to underpin high mortality rates of fish larvae, constituting a production bottleneck for the aquaculture industry. We employed 16S rRNA gene sequencing to determine whether treatment of live feed (rotifers and Artemia) with algal-derived, antibacterial metabolites could alter bacterial community structure of gilthead seabream (Sparus aurata) larvae in a larviculture facility. Owing to a large degree of sample-to-sample variation, pronounced 'legacy effects' of live feed manipulation on the total fish larvae bacterial community could not be verified. Notwithstanding, the approach induced shifts in relative abundance of specific bacterial phylotypes in both the live feed and fish larvae. Some phylotypes representing opportunistic taxa such as Stenotrophomonas, Pseudomonas and Klebsiella displayed reduced abundances in the bacterial community of fish larvae fed metabolite-treated vs. control live feed. Conversely, potentially beneficial phylotypes in the Alphaproteobacteria clade were consistently-although not significantly-promoted in the treated larval samples. These outcomes encourage future microbiome manipulation attempts to improve fish larviculture. However, successful host colonization and competition with resident symbionts are primary barriers that need to be overcome if live feeds are to be used as effective delivery systems of beneficial bacteria to fish larvae.

2021Journal article

Restricted access

Molecular Taxonomic Profiling of Bacterial Communities in a Gilthead Seabream (Sparus aurata) Hatchery

Publication . Califano, Gianmaria; Castanho, Sara; Soares, Florbela; Ribeiro, Laura; Cox, C. J.; Mata, Leonardo; Costa, Rodrigo

As wild fish stocks decline worldwide, land-based fish rearing is likely to be of increasing relevance to feeding future human generations. Little is known about the structure and role of microbial communities in fish aquaculture, particularly at larval developmental stages where the fish microbiome develops and host animals are most susceptible to disease. We employed next-generation sequencing (NGS) of 16S rRNA gene reads amplified from total community DNA to reveal the structure of bacterial communities in a gilthead seabream (Sparus aurata) larviculture system. Early-(2 days after hatching) and late-stage (34 days after hatching) fish larvae presented remarkably divergent bacterial consortia, with the genera Pseudoalteromonas, Marinomonas, Acinetobacter, and Acidocella (besides several unclassified Alphaproteobacteria) dominating the former, and Actinobacillus, Streptococcus, Massilia, Paracoccus, and Pseudomonas being prevalent in the latter. A significant reduction in rearing-water bacterial diversity was observed during the larviculture trial, characterized by higher abundance of the Cryomorphaceae family (Bacteroidetes), known to populate microniches with high organic load, in late-stage rearing water in comparison with early-stage rearing-water. Furthermore, we observed the recruitment, into host tissues, of several bacterial phylotypes-including putative pathogens as well as mutualists-that were detected at negligible densities in rearing-water or in the live feed (i.e., rotifers and artemia). These results suggest that, besides host-driven selective forces, both the live feed and the surrounding rearing environment contribute to shaping the microbiome of farmed gilthead sea-bream larvae, and that a differential establishment of host-associated bacteria takes place during larval development.

2017-02Journal article

Open access

The effect of live feeds bathed with the red seaweed Asparagopsis armata on the survival, growth and physiology status of Sparus aurata larvae

Publication . Castanho, Sara; Califano, Gianmaria; Soares, F.; Costa, Rodrigo; Mata, L.; Pousao-Ferreira, P.; Ribeiro, L.

Larval rearing is affected by a wide range of microorganisms that thrive in larviculture systems. Some seaweed species have metabolites capable of reducing the bacterial load. However, no studies have yet tested whether including seaweed metabolites on larval rearing systems has any effects on the larvae development. This work assessed the development of Sparus aurata larvae fed preys treated with an Asparagopsis armata product. Live prey, Brachionus spp. and Artemia sp., were immersed in a solution containing 0.5% of a commercial extract of A. armata (Ysaline 100, YSA) for 30 min, before being fed to seabream larvae (n = 4 each). In the control, the live feed was immersed in clear water. Larval parameters such as growth, survival, digestive capacity (structural-histology and functional-enzymatic activity), stress level (cortisol content), non-specific immune response (lysozyme activity), anti-bacterial activity (disc-diffusion assay) and microbiota quantification (fish larvae gut and rearing water) were monitored. Fish larvae digestive capacity, stress level and non-specific immune response were not affected by the use of YSA. The number of Vibrionaceae was significantly reduced both in water and larval gut when using YSA. Growth was enhanced for YSA treatment, but higher mortality was also observed, especially until 10 days after hatching (DAH). The mortality peak observed at 8 DAH for both treatments, but higher for YSA, indicates larval higher susceptibility at this development stage, suggesting that lower concentrations of YSA should be used until 10 DAH. The application of YSA after 10 DAH onwards promotes a safer rearing environment.

2017-08Journal article

Restricted access