SUStainable production of HIgh quality aquaculture FISH using innovative tools and production strategies and integrating novel processing methods and cold chain management

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Impacts of high pressure processing conditions on the microbiome of sea bass fillets

Publication . Machado, Paulo Jorge Rodrigues; Power, Deborah; Pinto, Patrícia Isabel Silvestre

Fish and seafood products are some of the most important protein sources in human nutrition and more than 45% of the fish used for human consumption comes from aquaculture. However, fish products are easily perishable and often associated with human diseases, leading to development of different preservation methods. Recently, novel processing techniques like High Pressure Processing (HPP), that uses pressure to inactivate microbes without heat, are being optimized to extend shelf-life without affecting food quality. We used metagenomics (the global study of genetic material from environmental or organism samples) to characterize in a global way the microbes present in sea bass fillets treated with different pressures (300-600 MPa) and processing times (2-5 min) and after refrigerated storage for 1 or 11 days, contributing to optimize HPP of these products. We extracted and selected 42 DNA samples (of 14 experimental groups) based on their quantity and quality and sent them to a sequencing company to construct microbiome libraries based on the 16S rRNA gene sequencing. With the sequencing and bioinformatics analysis using QIIME it was possible to evaluate the impacts of HPP treatments on the bacterial microbiome of the samples. There was a decrease in bacterial load in the treated samples when compared to the control (confirmed by quantitative PCR of 16S), which was especially evident when we compared the control at 11 days with the treated samples at 11 days, notably in the 450MPa and 600MPa treatments. The most abundant genera of bacteria in the control fillets significantly changed after storage for 11 days, leading to a different composition to 300 MPa fillets and separated by PCoA from 450-600 MPa fillets. These had a microbiome more similar to the initial control fillets. These results will help optimizing HPP of fish fillets and identifying the main genera of deterioration bacteria and HPP effects.

2021-12-09Master thesis

Open Access

The impact of egg thermal regimes on the response to food deprivation and refeeding in juvenile European sea bass (Dicentrarchus labrax)

Publication . Mateus, Ana; Costa, Rita; Jiménez, Javier; Sadoul, Bastien; Bégout, Marie Laure; Cousin, Xavier; Canario, Adelino; Power, Deborah

Fish are ectotherms and this means they are highly vulnerable to changes in ambient temperature, particularly during early developmental stages when temperature can induce persistent effects on phenotypic traits. In this study, the effect of egg incubation temperature on the response of juvenile European sea bass (Dicentrarchus labrax) to food deprivation and recovery after refeeding was assessed. Eggs were incubated at 11, 13.5 and 16 & DEG;C until hatching and then were reared at a common temperature until 9 months when fish were deprived of food for one week. The recovery from food deprivation was evaluated at 10 h and 2 days post-refeeding. Food deprivation in fish from eggs incubated at the highest temperature (16 & DEG;C) compared to 11 and 13.5 & DEG;C exhibited the most morphological and metabolic changes in the liver and foregut. Liver metabolism was changed as revealed by the significant reduction in lipid area and the increased number of hepatocyte nuclei. Foregut atrophy was coupled to a significant up-regulation of transcripts associated with gluconeogenesis (pck1) and peptide absorption (pept1). A modified metabolic response to the fast-refeed regime was revealed by the significantly decreased levels of plasma lactate, which may result from up-regulation of transcripts of the thyroid axis, deiodinase 2 (dio2) in the foregut. Fish incubated as eggs at a lower temperature (11 & DEG;C) exhibited less changes following the fast-refeed regime. Food deprivation did not significantly modify the morphology of the foregut and the liver parenchyma recovered sooner in fish from the 11 & DEG;C egg thermal regime compared to fish from the other thermal regimes following refeeding. The latter group of fish had a temporary stimulation of the GH-IGF axis with significant up-regulation of liver insulin-like growth factor I and II (igf-1 and igf-2) after fasting. The liver parenchyma of fish from the 13.5 & DEG;C egg thermal regime (the standard temperature of the hatchery stage) did not recover by the end of the experiment and transcripts of catalase (cat), encoding an antioxidant enzyme, were significantly downregulated compared to fish from the other egg thermal regimes. Our results suggest that thermal imprinting at the egg stage in European sea bass modified the juvenile metabolic response to food deprivation and the recovery response when feeding was resumed.

2023Journal article

Open Access

Thermal imprinting during embryogenesis modifies skin repair in juvenile European sea bass (Dicentrarchus labrax)

Publication . Mateus, Ana; Costa, Rita; Sadoul, Bastien; Bégout, Marie-Laure; Cousin, Xavier; Canario, Adelino; Power, Deborah

Fish skin is a multifunctional tissue that develops during embryogenesis, a developmental stage highly suscep-tible to epigenetic marks. In this study, the impact of egg incubation temperature on the regeneration of a cutaneous wound caused by scale removal in juvenile European sea bass was evaluated. Sea bass eggs were incubated at 11, 13.5 and 16 degrees C until hatching and then were reared at a common temperature until 9 months when the skin was damaged and sampled at 0, 1 and 3 days after scale removal and compared to the intact skin from the other flank. Skin damage elicited an immediate significant (p < 0.001) up-regulation of pcna in fish from eggs incubated at higher temperatures. In fish from eggs incubated at 11 C there was a significant (p < 0.001) up-regulation of krt2 compared to fish from higher thermal backgrounds 1 day after skin damage. Damaged epidermis was regenerated after 3 days in all fish irrespective of the thermal background, but in fish from eggs incubated at 11 C the epidermis was significantly (p < 0.01) thinner compared to other groups, had less goblet cells and less melanomacrophages. The thickness of the dermis increased during regeneration of wounded skin irrespective of the thermal background and by 3 days was significantly (p < 0.01) thicker than the dermis from the intact flank. The expression of genes for ECM remodelling (mmp9, colX alpha, col1 alpha 1, sparc, and angptl2b) and innate immunity (lyg1, lalba, sod1, csf-1r and ppar gamma) changed during regeneration but were not affected by egg thermal regime. Overall, the results indicate that thermal imprinting of eggs modifies the damage-repair response in juvenile sea bass skin.

2023Journal article

Open Access

High pressure processing of European sea bass (Dicentrarchus labrax) fillets and tools for flesh quality and shelf life monitoring

Publication . Tsironi, Theofania; Anjos, Liliana; Pinto, Patricia IS; Dimopoulos, George; Santos, Soraia; Santa, Cátia; Manadas, Bruno; Canario, Adelino; Taoukis, Petros; Power, Deborah

The effects of high pressure (HP:600 MPa, 5 min, 25 °C) on European sea bass fillets were investigated using microbiological, physicochemical and sensory indices, and “omics” technologies. HPP led to more than a 5 log(cfu/g) reduction in initial bacterial total viable counts and altered the bacterial microbiome, reducing the proportion of food spoilage genera. Lightness and hardness of the fish flesh significantly increased after HPP and were associated with modified muscle tissue histology, with fibers appearing fused and more compact in comparison to the unprocessed control. Sensory evaluation (based on a lower limit of 5 for overall acceptability scoring) indicated a shelf life of 11 days for untreated control samples and 2 months for the HP-treated fillets. Quantitative SWATH proteomics revealed 281 proteins that had modified levels between control and HP-processed fish flesh. The metagenomics and proteomics provided detailed insight into how the change in HP-processed sea bass fillets is linked to the modifications in the microbiome and proteome.

2019Journal article

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