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Microbial Ecology Jul 2023Although tunas represent a significant part of the global fish economy and a major nutritional resource worldwide, their microbiome still remains poorly documented....
Although tunas represent a significant part of the global fish economy and a major nutritional resource worldwide, their microbiome still remains poorly documented. Here, we conducted an analysis of the taxonomic composition of the bacterial communities inhabiting the gut, skin, and liver of two most consumed tropical tuna species (skipjack and yellowfin), from individuals caught in the Atlantic and Indian oceans. We hypothesized that each organ harbors a specific microbial assemblage whose composition might vary according to different biotic (sex, species) and/or abiotic (environmental) factors. Our results revealed that the composition of the tuna microbiome was totally independent of fish sex, regardless of the species and ocean considered. Instead, the main determinants of observed diversity were (i) tuna species for the gut and (ii) sampling site for the skin mucus layer and (iii) a combination of both parameters for the liver. Interestingly, 4.5% of all amplicon sequence variants (ASV) were shared by the three organs, highlighting the presence of a core-microbiota whose most abundant representatives belonged to the genera Mycoplasma, Cutibacterium, and Photobacterium. Our study also revealed the presence of a unique and diversified bacterial assemblage within the tuna liver, comprising a substantial proportion of potential histamine-producing bacteria, well known for their pathogenicity and their contribution to fish poisoning cases. These results indicate that this organ is an unexplored microbial niche whose role in the health of both the host and consumers remains to be elucidated.
Topics: Animals; Tuna; Hunting; Histamine; Bacteria; Microbiota
PubMed: 35962839
DOI: 10.1007/s00248-022-02096-4 -
Fish & Shellfish Immunology Nov 2019This review describes and summarizes the knowledge on established and experimental vaccines developed against viral and bacterial pathologies affecting the most... (Review)
Review
This review describes and summarizes the knowledge on established and experimental vaccines developed against viral and bacterial pathologies affecting the most important farmed marine finfish species present in the Mediterranean area, namely European seabass Dicentrarchus labrax, sea bream Sparus aurata, turbot Psetta maxima and meagre Argyrosomus regius. The diseases that have been recorded in seabass, sea bream and meagre are caused by bacteria Vibrio anguillarum, Photobacterium damselae, Tenacibaculum maritimum as well as by viruses such as Viral Encephalopathy and Retinopathy/Viral Nervous Necrosis and Lymphocystic disease. The main pathologies of turbot are instead bacteriosis provoked by Tenacibaculum maritimum, Aeromonas sp. and Vibrio anguillarum, and virosis by viral hemorrhagic septicaemia virus. Some vaccines have been optimized and are now regularly available for the majority of the above-mentioned pathogens. A measurable immune protection has been conferred principally against Vibrio anguillarum, Photobacterium damselae sub. piscicida and VER/VNN.
Topics: Animals; Bacterial Infections; Bacterial Vaccines; Fish Diseases; Fishes; Mediterranean Sea; Viral Vaccines; Virus Diseases
PubMed: 31580938
DOI: 10.1016/j.fsi.2019.09.065 -
FEMS Microbiology Ecology Sep 2022Like other seafood products, tuna is highly perishable and sensitive to microbial spoilage. Its consumption, whether fresh or canned, can lead to severe food poisoning...
Like other seafood products, tuna is highly perishable and sensitive to microbial spoilage. Its consumption, whether fresh or canned, can lead to severe food poisoning due to the activity of specific microorganisms, including histamine-producing bacteria. Yet, many grey areas persist regarding their ecology, conditions of emergence, and proliferation in fish. In this study, we used 16S rRNA barcoding to investigate postmortem changes in the bacteriome of fresh and brine-frozen yellowfin tuna (Thunnus albacares), until late stages of decomposition (i.e. 120 h). The results revealed that despite standard refrigeration storage conditions (i.e. 4°C), a diverse and complex spoilage bacteriome developed in the gut and liver. The relative abundance of spoilage bacterial taxa increased rapidly in both organs, representing 82% of the bacterial communities in fresh yellowfin tuna, and less than 30% in brine-frozen tuna. Photobacterium was identified as one of the dominant bacterial genera, and its temporal dynamics were positively correlated with histamine concentration in both gut and liver samples, which ultimately exceeded the recommended sanitary threshold of 50 ppm in edible parts of tuna. The results from this study show that the sanitary risks associated with the consumption of this widely eaten fish are strongly influenced by postcapture storage conditions.
Topics: Animals; Bacteria; Food Microbiology; Histamine; Microbiota; RNA, Ribosomal, 16S; Salts; Tuna
PubMed: 36124730
DOI: 10.1093/femsec/fiac110 -
Food Microbiology Oct 2021Photobacterium spp. occur frequently in marine environments but have been recently also found as common spoilers on chilled meats. The environmental conditions in these...
Photobacterium spp. occur frequently in marine environments but have been recently also found as common spoilers on chilled meats. The environmental conditions in these ecological niches differ especially regarding salinity and ambient pressure. Linking the occurrence of photobacteria in different niches may elucidate its ecology and bring insights for the food industry. We investigated tolerance of Photobacterium (P.) phosphoreum and P. carnosum strains to high hydrostatic pressure and salinity and aligned our observations with presence of relevant genes. The strains were isolated from packaged meats and salmon (or the sea) to identify adaptations to marine and terrestrial habitats. Growth of all P. carnosum strains was reduced by 40 MPa hydrostatic pressure and >3% sodium chloride, suggesting loss of traits associated with marine habitats. In contrast, P. phosphoreum strains were only slightly affected, suggesting general adaptation to marine habitats. In accordance, these strains had gene clusters associated with marine niches, e.g. flagellar and lux-operons, being incomplete in P. carnosum. Occurrence of P. carnosum strains on packaged salmon and P. phosphoreum strains on meats therefore likely results from cross-contamination in meat and fish processing. Still, these strains showed intermediate traits regarding pressure- and halotolerance, suggesting developing adaptation to their respective environment.
Topics: Animals; Cattle; Chickens; Food Microbiology; Hydrostatic Pressure; Meat; Photobacterium; Salmon; Seawater; Sodium Chloride
PubMed: 34119089
DOI: 10.1016/j.fm.2020.103679 -
Detection, Identification, and Inactivation of Histamine-forming Bacteria in Seafood: A Mini-review.Journal of Food Protection Mar 2023Seafood is one of the essential sources of nutrients for the human diet. However, they can be subject to contamination and can cause foodborne illnesses, including... (Review)
Review
Seafood is one of the essential sources of nutrients for the human diet. However, they can be subject to contamination and can cause foodborne illnesses, including scombroid fish poisoning caused by histamine. Many microorganisms can produce enzymes that eventually decompose endogenous histidine to histamine in postmortem fish muscles and tissues. One of these is histamine-forming bacteria (HFB), primarily found in the gills, gut, and skin of fishes. Previous studies linked a plethora of Gram-negative HFB including Morganella spp. and Photobacterium spp. to scombroid fish poisoning from many types of seafood, especially the Scombridae family. These bacteria possess the hdc gene to produce histidine decarboxylase enzyme. It was reported that Gram-negative HFB produced 6345 ppm in tuna and 1223 ppm in Spanish mackerel. Interestingly, Gram-positive HFB have been isolated in the seafood samples with lower histamine levels. It suggests that Gram-negative HFB are the major contributor to the accumulation of histamine in seafood. Several analytical methods are available to detect and identify HFB and their histamine metabolites from seafood substrates. Rapid test kits can be used in food production settings for early detection of histamine to avoid food intoxication. Furthermore, high hydrostatic pressure and irradiation treatment could prevent the proliferation of HFB and inactivate the existing histidine decarboxylase (HDC) activity. As demonstrated in different seafood model systems, the HDC activity was deactivated at a maximum high hydrostatic pressure level of 400 MPa. The complete inactivation of HFB was achieved by gamma irradiation at a dose of 4.0 kGy. Other postharvest treatments, like enzymatic degradation and electrolyzed oxidizing water, were studied as sustainable methods for bacterial growth prevention and enzyme inactivation. However, other HFB react differently to these treatment conditions, and further studies are recommended.
Topics: Animals; Humans; Histamine; Histidine Decarboxylase; Bacteria; Seafood; Tuna; Gram-Negative Bacteria; Fishes; Foodborne Diseases
PubMed: 36916556
DOI: 10.1016/j.jfp.2023.100049 -
Journal of Agricultural and Food... Nov 2022The malonyl-CoA:ACP transacylase (MAT) domain is responsible for the selection and incorporation of malonyl building blocks in the biosynthesis of polyunsaturated fatty...
The malonyl-CoA:ACP transacylase (MAT) domain is responsible for the selection and incorporation of malonyl building blocks in the biosynthesis of polyunsaturated fatty acids (PUFAs) in eukaryotic microalgae () and marine bacteria (, , and ). Elucidation of the structural basis underlying the substrate specificity and catalytic mechanism of the MAT will help to improve the yield and quality of PUFAs. Here, a methodology guided by molecular dynamics simulations was carried out to identify and mutate specificity-conferring residues within the MAT domain of . Combining mutagenesis, cell-free protein synthesis, and biochemical assay, we dissected nearby interactions and molecular mechanisms relevant for binding and catalysis and found that the reorientation of the Ser154 C-O bond establishes distinctive proton-transfer chains (His153-Ser154 and Asn235-His153-Ser154) for catalysis. Gln66 can be replaced by tyrosine to shorten the distance between His153 (N) and Ser154 (O), which facilitates a faster proton-transfer rate, allowing better use of acyl substrates than the wild type. Furthermore, we screened a mutant that displayed an 18.4% increase in PUFA accumulation. These findings provide important insights into the study of MAT through protein engineering and will benefit dissecting the molecular mechanisms of other PUFA-related catalytic domains.
Topics: Malonyl Coenzyme A; Protons; Acyl-Carrier Protein S-Malonyltransferase; Acyltransferases; Stramenopiles; Fatty Acids, Unsaturated
PubMed: 36264009
DOI: 10.1021/acs.jafc.2c05447 -
Journal of Applied Microbiology Jul 2023Aquaculture, a noteworthy food production sector, is confronted with disease occurrences. Treatment of aquaculture pathogens with antibiotics is often rendered... (Review)
Review
Aquaculture, a noteworthy food production sector, is confronted with disease occurrences. Treatment of aquaculture pathogens with antibiotics is often rendered ineffective due to biofilm formation and the development of resistant strains. Marine ecosystems encompass unusual microorganisms that produce novel bioactive compounds, including agents that could be used as alternatives to antibiotics. Moreover, biomass and/or biomolecules associated with these microorganisms could act as feed supplements to enhance the overall health of aquaculture species' and improve water quality parameters. The present review summarizes the contents of studies on such marine microorganisms with the potential to be developed as agents for tackling bacterial diseases in the aquaculture segment. Bioactive compounds produced by marine bacteria are known to inhibit biofilm-associated infections mediated by their bactericidal properties (produced by Bacillus, Vibrio, Photobacterium, and Pseudoalteromonas species), surfactant activity (obtained from different species of Bacillus and Staphylococcus lentus), anti-adhesive activity (derived from Bacillus sp. and Brevibacterium sp.), and quorum sensing inhibition. Several marine fungal isolates capable of producing antibacterial agents have also been effective in inhibiting aquaculture-associated pathogens. Another strategy followed by investigators to reduce the severity of infections is the use of bacterial, yeast, and microalgae biomass as feed supplements, probiotics, and immunostimulants. In some cases, marine microalgae have been employed as sustainable alternatives to fish oil and fish meal without compromising on nutritional quality. Their inclusion in aquaculture feed has enhanced growth, favored better survival of cultured species, and improved water quality parameters. Marine microorganisms (by providing effective bioactive compounds and being used as feed supplements) could enable aquaculture practices to be more sustainable in the future.
Topics: Ecosystem; Aquaculture; Anti-Infective Agents; Bacillus; Vibrio; Anti-Bacterial Agents
PubMed: 37365690
DOI: 10.1093/jambio/lxad128 -
International Journal of Systematic and... Oct 2021A Gram-stain-negative, aerobic, motile, short rod-shaped, catalase-negative and oxidase-positive bacterium, strain CAU 1568, was isolated from marine sediment sand...
A Gram-stain-negative, aerobic, motile, short rod-shaped, catalase-negative and oxidase-positive bacterium, strain CAU 1568, was isolated from marine sediment sand sampled at Sido Island in the Republic of Korea. The optimum conditions for growth were at 25-30 °C, at pH 6.5-8.5 and with 0-4.0 % (w/v) NaCl. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain CAU 1568 was a member of the genus with high similarity to JCM 30852 (97.7 %), KACC 17089 (97.3 %) and LMG F28894 (97.3 %). The predominant cellular fatty acids were C, summed feature 3 (C 6 and/or C 7) and summed feature 8 (C 7 and/or C 6), with Q-8 as the major of isoprenoid quinone. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerols, phosphatidylcholine, phosphatidylethanolamine, phospholipid, two aminophospholipids and three unidentified lipids. The whole genome size of strain CAU 1568 was 4.8 Mb with 50.1 mol% G+C content; including 38 contigs and 4233 protein-coding genes. These taxonomic data support CAU 1568 as representing a novel species, for which the name sp. nov. is proposed. The type strain of this novel species is CAU 1568 (=KCTC 82404=MCCC 1K05668).
Topics: Bacterial Typing Techniques; Base Composition; DNA, Bacterial; Fatty Acids; Geologic Sediments; Islands; Phospholipids; Photobacterium; Phylogeny; RNA, Ribosomal, 16S; Republic of Korea; Sand; Seawater; Sequence Analysis, DNA; Ubiquinone
PubMed: 34605765
DOI: 10.1099/ijsem.0.005034 -
Environmental Microbiome Oct 2023Coral reefs are one of the most biodiverse and productive ecosystems, providing habitat for a vast of species. Reef-building scleractinian corals with a symbiotic...
BACKGROUND
Coral reefs are one of the most biodiverse and productive ecosystems, providing habitat for a vast of species. Reef-building scleractinian corals with a symbiotic microbiome, including bacteria, archaea, viruses and eukaryotic microbes, are referred to coral holobionts. Among them, coral diseases, mainly caused by Vibrio spp., have significantly contributed to the loss of coral cover and diversity. Habitat filtering across the globe has led to a variety structure of marine bacterial communities. Coral species, quantity and characteristics are significant differences between the Xisha Islands and Daya Bay (Guangdong Province). Thus, the Vibrio communities may be distinct between coral rich and poor areas.
RESULTS
Through comparison of Vibrio dynamics between coral-rich (Xisha Islands) and coral-poor (Daya Bay) locations, we uncovered differences in Vibrio abundance, diversity, community composition and assembly mechanisms associated with corals. The higher abundance of Vibrio in coral rich areas may indicate a strong interaction between vibrios and corals. V. campbellii, Paraphotobacterium marinum and V. caribbeanicus were widely distributed in both coral rich and poor areas, likely indicating weak species specificity in the coral-stimulated growth of Vibrio. Random-forest prediction revealed Vibrio species and Photobacterium species as potential microbial indicators in the coral rich and coral poor areas, respectively. Ecological drift rather than selection governed the Vibrio community assembly in the Xisha Islands. Comparatively, homogenizing selection was more important for the Daya Bay community, which may reflect a role of habitat filtration.
CONCLUSION
This study revealed the different distribution pattern and assembly mechanism of Vibrio spp. between coral rich and poor areas, providing the background data for the research of Vibrio community in coral reef areas and may help the protection of coral reef at the biological level. The main reasons for the difference were different number and species of corals, environmental (e.g., temperature) and spatial factors. It reflected the strong interaction between Vibrio and corals, and provided a new perspective for the investigation of Vibrio in coral reef ecosystem.
PubMed: 37872593
DOI: 10.1186/s40793-023-00532-7 -
Chemosphere Dec 2023Marine pollution and bacterial disease outbreaks are two closely related dilemmas that impact marine fish production from fisheries and mariculture. Oil, heavy metals,... (Review)
Review
Marine pollution and bacterial disease outbreaks are two closely related dilemmas that impact marine fish production from fisheries and mariculture. Oil, heavy metals, agrochemicals, sewage, medical wastes, plastics, algal blooms, atmospheric pollutants, mariculture-related pollutants, as well as thermal and noise pollution are the most threatening marine pollutants. The release of these pollutants into the marine aquatic environment leads to significant ecological degradation and a range of non-infectious disorders in fish. Marine pollutants trigger numerous fish bacterial diseases by increasing microbial multiplication in the aquatic environment and suppressing fish immune defense mechanisms. The greater part of these microorganisms is naturally occurring in the aquatic environment. Most disease outbreaks are caused by opportunistic bacterial agents that attack stressed fish. Some infections are more serious and occur in the absence of environmental stressors. Gram-negative bacteria are the most frequent causes of these epizootics, while gram-positive bacterial agents rank second on the critical pathogens list. Vibrio spp., Photobacterium damselae subsp. Piscicida, Tenacibaculum maritimum, Edwardsiella spp., Streptococcus spp., Renibacterium salmoninarum, Pseudomonas spp., Aeromonas spp., and Mycobacterium spp. Are the most dangerous pathogens that attack fish in polluted marine aquatic environments. Effective management strategies and stringent regulations are required to prevent or mitigate the impacts of marine pollutants on aquatic animal health. This review will increase stakeholder awareness about marine pollutants and their impacts on aquatic animal health. It will support competent authorities in developing effective management strategies to mitigate marine pollution, promote the sustainability of commercial marine fisheries, and protect aquatic animal health.
Topics: Animals; Bacterial Infections; Fishes; Bacteria; Gram-Negative Bacteria; Environmental Pollutants; Fish Diseases
PubMed: 37806325
DOI: 10.1016/j.chemosphere.2023.140366