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1.
PLoS One ; 15(7): e0236601, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32730353

RESUMO

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), exhibit antibacterial and anti-inflammatory activities. Furthermore, diets rich in n-3 PUFAs are known to improve disease resistance and limit pathogen infection in commercial aquaculture fishes. In this study, we examined the effects of transgenic overexpression of n-3 PUFA biosynthesis genes on the physiological response to bacterial infection in tilapia. We first established tilapia strains with single or dual expression of salmon delta-5 desaturase and/or delta-6 desaturase and then challenged the fish with Vibrio vulnificus infection. Interestingly, our data suggest that n-3 PUFA-mediated alterations in gut microbiota may be important in determining disease outcome via effects on immune response of the host. Both liver- and muscle-specific single and dual expression of delta-5 desaturase and delta-6 desaturase resulted in higher n-3 PUFA content in transgenic fish fed with a LO basal diet. The enrichment of n-3 PUFAs in dual-transgenic fish is likely responsible for their improved survival rate and comparatively reduced expression of inflammation- and immune-associated genes after V. vulnificus infection. Gut microbiome analysis further revealed that dual-transgenic tilapia had high gut microbiota diversity, with low levels of inflammation-associated microbiota (i.e., Prevotellaceae). Thus, our findings indicate that dual expression of transgenic delta-5 and delta-6 desaturase in tilapia enhances disease resistance, an effect that is associated with increased levels of n-3 PUFAs and altered gut microbiota composition.


Assuntos
Resistência à Doença , Ácidos Graxos Dessaturases/metabolismo , Proteínas de Peixes/metabolismo , Microbioma Gastrointestinal , Linoleoil-CoA Desaturase/metabolismo , Tilápia/microbiologia , Vibrio vulnificus/patogenicidade , Animais , Animais Geneticamente Modificados/genética , Animais Geneticamente Modificados/microbiologia , Dieta/veterinária , Análise Discriminante , Resistência à Doença/genética , Ácidos Docosa-Hexaenoicos/metabolismo , Ácidos Graxos Dessaturases/genética , Ácidos Graxos Ômega-3/metabolismo , Doenças dos Peixes/microbiologia , Doenças dos Peixes/patologia , Proteínas de Peixes/genética , Expressão Gênica , Análise dos Mínimos Quadrados , Linoleoil-CoA Desaturase/genética , Tilápia/genética , Vibrioses/patologia , Vibrioses/veterinária
2.
Aquat Toxicol ; 224: 105494, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32422488

RESUMO

Little is known about the impacts of dietary exposure to inorganic mercury (Hg) for a long duration on the health indicators, growth, and disease resistance in Oreochromis niloticus. Accordingly, the current study was designed to assess the effects of Hg contaminated diets on blood biochemistry, growth, chemical composition, Hg bioaccumulation in the tissues, histopathology of liver and head kidneys, and disease resistance to Aeromonas hydrophila of O. niloticus. Also, the efficiency of citronella oil, geranium oil (GO), curcumin (CUR), Bacillus toyonensis (BT), and Bacillus subtilis (BS) as dietary supplements on reversing the negative impacts of Hg were assessed. A total of 240 tilapia fingerlings were assigned to eight dietary treatments fed on the basal diet (G1), G1 diet contaminated with 50 ppm Hg (G2), whereas the other groups fed the G2 diet and enriched with 400 mg CO (G3), 400 mg GO (G4), 200 mg CUR (G5), 7 × 107 cells BT (G6), 7 × 107 cells BS (G7), and 7 × 107 BT + BS/ kg diet (G8) for 16 weeks. The obtained results showed that fish fed on the G2 diet had significantly impaired growth performance indicators, blood parameters, and resistance to bacterial infection compared with fish in the control group. Additionally, distinct pathological perturbations in liver and head kidneys were observed. In contrast, fish groups G3 to G8 had a significant enhancement in the growth performance, Hg bioaccumulation in fish tissues, blood biochemistry, and resistance against A. hydrophila infection compared with fish in the G2 group. Maximum improvement was recorded in G5, G6, and G8. Conclusively, from both health and an economic point of view, these results suggested that several benefits might be gained by adding these additives, especially CUR, BT, and BT + BS, on growth enhancement and ameliorating Hg negative impacts in O. niloticus.


Assuntos
Ração Animal/análise , Bioacumulação , Ciclídeos/crescimento & desenvolvimento , Resistência à Doença/efeitos dos fármacos , Doenças dos Peixes/prevenção & controle , Infecções por Bactérias Gram-Negativas/veterinária , Mercúrio/toxicidade , Poluentes Químicos da Água/toxicidade , Aeromonas hydrophila/patogenicidade , Animais , Ciclídeos/imunologia , Ciclídeos/microbiologia , Dieta , Suplementos Nutricionais , Resistência à Doença/imunologia , Doenças dos Peixes/imunologia , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/imunologia , Infecções por Bactérias Gram-Negativas/microbiologia , Rim Cefálico/efeitos dos fármacos , Rim Cefálico/metabolismo , Rim Cefálico/patologia , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Mercúrio/metabolismo , Poluentes Químicos da Água/metabolismo
3.
Vet Res Commun ; 44(2): 61-72, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32472344

RESUMO

Aeromonas salmonicida is one of the most important pathogens in salmonids and non-salmonids species. Nevertheless, very little was reported in cyprinids about A. salmonicida infection. Hence, a pathogenic A. salmonicida subsp. salmonicida, namely isolate GCA-518, was isolated from diseased crucian carp Carassius auratus. Its optimal growth conditions were at 28 °C, pH 7.0 and 1.5% NaCl. Furthermore, the quantitative real-time PCR (qPCR) targeting serine protease (aspA) gene was established for rapid detection of the lowest limit of 5.6 × 102 copies per reaction. The pathogenicity was confirmed in crucian carp by intraperitoneal infection. Histopathologic examination displayed multifocal necrosis and infiltration of inflammatory cells in gill, liver, kidney and intestine. This is the first report on typical A. salmonicida infection in cultured crucian carp.


Assuntos
Aeromonas salmonicida/fisiologia , Carpas , Doenças dos Peixes/diagnóstico , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Aeromonas salmonicida/genética , Aeromonas salmonicida/isolamento & purificação , Aeromonas salmonicida/patogenicidade , Animais , Proteínas de Bactérias/genética , Doenças dos Peixes/patologia , Infecções por Bactérias Gram-Negativas/diagnóstico , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/patologia , Limite de Detecção , Reação em Cadeia da Polimerase em Tempo Real , Serina Endopeptidases/genética
4.
Mycotoxin Res ; 36(3): 311-318, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32372256

RESUMO

Fusarium infections have been reported in aquatic animals, but are still poorly investigated in wild salmonids. The aim of the study was to determine the impact of the fungi and their toxins on the health status of brown trout (Salmo trutta morpha trutta) migrating from the Baltic Sea to the freshwater. Individuals from the wild brown trout population exhibiting ulcerative skin lesions were collected from the Slupia River in Poland and subjected to microbiological, histopathological, and hematological examinations, as well as toxicological analysis for a presence of mycotoxins. The results of microflora isolation from the brown trout skin samples revealed the presence of conditionally pathogenic bacteria and fungi classified by molecular techniques as Fusarium spp. Toxicological analysis allowed for detection of zearalenone (ZEN) in the liver, kidney, and gastrointestinal tract of the fish. In several cases, there was α-zearalenone (α-ZEL) identified at trace levels in the liver, as well as sterigmatocystin and enniatin B at low levels in the kidney and the liver. Histopathological examination revealed the presence of fungal hyphae disrupting the epidermis and penetrating into the necrotic dermis and hypodermis. The decreased values of the blood parameters, i.e., hemoglobin concentration (HGB), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and white blood cell count (WBC), were indicative of osmoregulation failure being a consequence of the skin damage. The results of the study provide new information regarding Fusarium sp. infection in brown trout and serve as the basis for further research on the potential impact of the fungi and their mycotoxins on the Baltic salmonid population, including their role in ulcerative dermal necrosis.


Assuntos
Doenças dos Peixes/microbiologia , Fusarium/metabolismo , Micotoxinas/toxicidade , Necrose/veterinária , Dermatopatias/veterinária , Animais , Doenças dos Peixes/patologia , Fusarium/química , Micotoxinas/análise , Micotoxinas/metabolismo , Necrose/microbiologia , Necrose/patologia , Polônia , Pele/microbiologia , Dermatopatias/microbiologia , Dermatopatias/patologia , Truta/microbiologia
5.
Res Vet Sci ; 131: 177-185, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32388020

RESUMO

Heat-killed (HK) Bacillus sp. SJ-10 (B), HK Lactobacillus plantarum (P), and their combination were dietary supplemented to olive flounder (Paralichthys olivaceus) to quantify the effects on growth, innate immunity, and disease resistance. Four test diets were supplied: a control feed free of HK probiotics, 1 × 108 CFUs g-1 single treatments of each of HK B (HKB) and HK P (HKP), and an equal proportion of (0.5 HKB + 0.5 HKP) × 108 CFUs g-1 (HKB0.5 HKP0.5). At 8 weeks of completion feeding trail, HKB0.5 HKP0.5 significantly (P < .05) improved growth, feed utilization, and nonspecific immune parameters (respiratory burst and superoxide dismutase) compared to the control group. Similarly, serum lysozyme and myeloperoxidase activities were higher in both HKB and HKB0.5HKP0.5 groups. The levels of pro-inflammatory cytokine IL-6 in the liver and IL-1ß in the liver, kidney, and spleen were also improved in the treatments, but microvilli length was only increased in HKB0.5HKP0.5. After Streptococcus iniae 1 × 108 CFUs mL-1 challenged; HKB and HKB0.5HKP0.5 had a higher survival than control and HKP. Overall, dietary administration of synergy HK probiotics elevated growth, cellular and humoral immunity, and streptococcosis resistance in olive flounder.


Assuntos
Bacillus , Dieta/veterinária , Linguado , Lactobacillus plantarum , Probióticos/farmacologia , Animais , Citocinas/genética , Citocinas/imunologia , Citocinas/metabolismo , Suplementos Nutricionais , Doenças dos Peixes/imunologia , Doenças dos Peixes/microbiologia , Doenças dos Peixes/prevenção & controle , Regulação da Expressão Gênica/efeitos dos fármacos , Imunidade Celular/efeitos dos fármacos , Imunidade Inata/efeitos dos fármacos , Infecções Estreptocócicas/imunologia , Streptococcus iniae
6.
Mar Environ Res ; 157: 104864, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32275501

RESUMO

Microbial contamination of aggregates collected near an Atlantic salmon farm, in the Cherbourg roadstead, was followed monthly over one year to study the dynamics of Vibrio spp. and explore their impact on farmed fish. Salmon state of health was followed through blood and histopathological analyses. Vibrio were systematically found in aggregates with particularly high concentration in August. The Splendidus clade was strongly dominant in aggregates as well as in gills, and an increase in Vibrio diversity was observed in summer and autumn. Results did not demonstrate that aggregates directly impact the bacterial community of gills, but they suggested an aggregates-gills interaction. Gill contamination was correlated with water temperature and probably impacted by amoebae. Vibrio renipiscarius and Vibrio toranzoniae were isolated in North Atlantic for the first time. A better understanding of the interaction between marine aggregates, Vibrio spp. and fish is essential to improve salmon cage farming.


Assuntos
Aquicultura , Doenças dos Peixes/microbiologia , Salmo salar/microbiologia , Vibrio/isolamento & purificação , Animais , Oceano Atlântico , Brânquias/microbiologia , Estações do Ano , Vibrio/classificação
7.
Lett Appl Microbiol ; 71(1): 26-38, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32248555

RESUMO

One of the major problems to be addressed in aquaculture is the prominence of antimicrobial resistance (AMR). The occurrence of bacterial infections in cultured fishes promotes the continuous use of antibiotics in aquaculture, which results in the selection of proliferated antibiotic-resistant bacteria and increases the possibility of transfer to the whole environment through horizontal gene transfer. Hence, the accurate cultivation-dependent and cultivation-independent detection methods are very much crucial for the immediate and proper management of this menace. Antimicrobial resistance determinants carrying mobile genetic transfer elements such as transposons, plasmids, integrons and gene cassettes need to be specifically analysed through molecular detection techniques. The susceptibility of microbes to antibiotics should be tested at regular intervals along with various biochemical assays and conjugation studies so as to determine the extent of spread of AMR. Advanced omic-based and bioinformatic tools can also be incorporated for understanding of genetic diversity. The present review focuses on different detection methods to unearth the complexity of AMR in aquaculture. This monitoring helps the authorities to curb the use of antibiotics, commencement of appropriate management measures and adequate substitute strategies in aquaculture. The long battle of AMR could be overcome by the sincere implementation of One Health approach. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of antibiotics and increased antimicrobial resistance (AMR) are of major concerns in aquaculture industry. This could result in global health risks through direct consumption of cultured fishes and dissemination of AMR to natural environment through horizontal gene transfer. Hence, timely detection of the antimicrobial-resistant pathogens and continuous monitoring programmes are inevitable. Advanced microbiological, molecular biological and omic-based tools can unravel the menace to a great extent. This will help the authorities to curb the use of antibiotics and implement appropriate management measures to overcome the threat.


Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Doenças dos Peixes/microbiologia , Peixes/microbiologia , Animais , Aquicultura , Bactérias/genética , Infecções Bacterianas/tratamento farmacológico , Infecções Bacterianas/veterinária , Transferência Genética Horizontal , Integrons/genética , Plasmídeos/genética , Uso Excessivo de Medicamentos Prescritos
8.
J Fish Dis ; 43(5): 519-529, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32285473

RESUMO

Vibrio vulnificus, Edwardsiella anguillarum and Aeromonas hydrophila are three common bacterial pathogens in cultivated eels. To protect farming eels from infection by these pathogens, a trivalent outer membrane protein (OMP) containing partial sequences of OmpU from V. vulnificus, OmpA from E. anguillarum and OmpII from A. hydrophila was expressed and purified; then, the OMP was used as a vaccine to immunize Japanese eels (Anguilla japonica). Whole-blood cell proliferation, antibody titres and complement and lysozyme activities were detected at different days post-immunization (dpi), and the relative per cent survival (RPS) was determined after eels were infected with V. vulnificus, E. anguillarum or A. hydrophila at 28 dpi. The results showed that the OMP significantly stimulates the antibody titres. At 14 days after the challenge (i.e. at 28 dpi), the RPS of OMP against V. vulnificus, E. anguillarum and A. hydrophila was 20%, 70% and 11.1%, respectively. The construction, expression and immunogenicity of a trivalent Omp were reported for the first time, and this study will provide a valuable reference for the development of fish multiplex vaccines.


Assuntos
Aeromonas hydrophila/genética , Proteínas da Membrana Bacteriana Externa/genética , Edwardsiella/genética , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Vibrio vulnificus/genética , Aeromonas hydrophila/metabolismo , Anguilla , Animais , Proteínas da Membrana Bacteriana Externa/imunologia , Edwardsiella/metabolismo , Infecções por Enterobacteriaceae/microbiologia , Infecções por Enterobacteriaceae/veterinária , Infecções por Bactérias Gram-Negativas/microbiologia , Vibrioses/microbiologia , Vibrioses/veterinária , Vibrio vulnificus/imunologia
9.
J Fish Dis ; 43(5): 621-629, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32293041

RESUMO

Vibriosis outbreaks due to Vibrio ordalii occur globally, but Chilean salmon aquaculture, in particular, has suffered significant monetary losses in the last 15 years. Little is known about the virulence mechanisms employed by V. ordalii. However, most Vibrio pathogens (e.g., Vibrio anguillarum, a very close taxonomic species) present outer membrane vesicles (OMVs) that are released extracellularly and implicated in the delivery of virulence factors to host cells. This study provides the first reported evidence of the fish pathogen V. ordalii producing and releasing OMVs under normal growth conditions. Analyses were conducted with the V. ordalii strain Vo-LM-18 and the type strain ATCC 33509T . For comparative purposes, the reference strain V. anguillarum ATCC 43307 was employed. The average size for the three Vibrio strains was 0.215 ± 0.6 µm (via scanning electron microscopy) or between 0.19 and 1.8 µm (via dynamic light scattering), with each bacterium presenting a wide range. SDS-PAGE revealed similarities in OMV patterns, but neither total nor external proteins were identical. Comparing V. ordalii ATCC 33509T and Vo-LM-18, bands were most evident in the total proteins, and the greatest degree of similarity in OMV profiles was between 37 and 50 kDa. The purified OMVs demonstrated haemolytic enzyme activity, which could play a role during V. ordalii infection. These data represent an initial step towards gaining new insights into this virulence factor, of which a lot is known in other pathogenic microorganisms.


Assuntos
Membrana Externa Bacteriana/metabolismo , Vesículas Extracelulares/metabolismo , Doenças dos Peixes/microbiologia , Salmo salar , Vibrioses/veterinária , Vibrio/fisiologia , Vibrio/patogenicidade , Animais , Vibrioses/microbiologia , Virulência
10.
J Vet Diagn Invest ; 32(3): 356-362, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32310022

RESUMO

Flavobacterium columnare is the causative agent of columnaris disease in a variety of fish hosts. Using modifications to previously established protocols, a quantitative PCR (qPCR) assay was validated for the detection of 2 predominant F. columnare genomovars. The oligonucleotide primer and probe combination was designed to amplify a 203-bp region of the chondroitin AC lyase gene (GenBank AY912281) of F. columnare. There were no significant differences in amplification between genomovars. Comparable quantities of genomic DNA from 10 F. columnare strains, 5 representatives of each genomovar, produced similar results. Serial dilutions of purified PCR product demonstrated the limit of sensitivity for the assay was ~ 10 copies per reaction. The presence of gill and spleen tissue did not significantly affect the sensitivity of the assay. Comparably, bacterial DNA detected from the liver and kidney was less sensitive than pure bacterial DNA. However, detection from these tissues was within one order of magnitude of other tissues, indicating this reduction may have minimal analytic significance. This validated assay was used to approximate the minimum infectious dose for F. columnare isolate 94-081 in channel catfish and assess bacterial loads in gill and kidney tissues 48 h post-infection.


Assuntos
Doenças dos Peixes/diagnóstico , Infecções por Flavobacteriaceae/veterinária , Flavobacterium/isolamento & purificação , Ictaluridae , Reação em Cadeia da Polimerase em Tempo Real/veterinária , Animais , Doenças dos Peixes/microbiologia , Infecções por Flavobacteriaceae/diagnóstico , Infecções por Flavobacteriaceae/microbiologia , Flavobacterium/classificação , Flavobacterium/genética , Genótipo , Reação em Cadeia da Polimerase em Tempo Real/métodos
11.
Int J Syst Evol Microbiol ; 70(3): 2034-2048, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32160147

RESUMO

Francisella noatunensis is a fastidious facultative intracellular bacterial pathogen that causes 'piscine francisellosis', a serious disease affecting both marine and fresh water farmed and wild fish worldwide. Currently two F. noatunensis subspecies are recognized, i.e. F. noatunensis subsp. noatunensis and F. noatunensis subsp. orientalis. In the present study, the taxonomy of F. noatunensis was revisited using a polyphasic approach, including whole genome derived parameters such as digital DNA-DNA hybridization, whole genome average nucleotide identity (wg-ANIm), whole genome phylogenetic analysis, whole genome G+C content, metabolic fingerprinting and chemotaxonomic analyses. The results indicated that isolates belonging to F. noatunensis subsp. orientalis represent a phenotypically and genetically homogenous taxon, clearly distinguishable from F. noatunensis subsp. noatunensis that fulfils requirements for separate species status. We propose, therefore, elevation of F. noatunensis subsp. orientalis to the species rank as Francisella orientalis sp. nov. with the type strain remaining as Ehime-1T (DSM 21254T=LMG 24544T). Furthermore, we identified sufficient phenotypic and genetic differences between F. noatunensis subsp. noatunensis recovered from diseased farmed Atlantic salmon in Chile and those isolated from wild and farmed Atlantic cod in Northern Europe to warrant proposal of the Chilean as a novel F. noatunensis subspecies, i.e. Francisella noatunensis subsp. chilensis subsp. nov. with strain PQ1106T (CECT 9798T=NCTC14375T) as the type strain. Finally, we emend the description of F. noatunensis by including further metabolic information and the description of atypical strains.


Assuntos
Francisella/classificação , Filogenia , Animais , Técnicas de Tipagem Bacteriana , Chile , DNA Bacteriano/genética , Europa (Continente) , Doenças dos Peixes/microbiologia , Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
12.
Parasitol Res ; 119(4): 1221-1236, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32179988

RESUMO

Members of the myxozoan genus Kudoa (Myxosporea: Multivalvulida: Kudoidae) are characterized as having four or more shell valves in a myxospore, with a corresponding number of polar capsules. Certain Kudoa spp. are critical pathogens in fish, causing postmortem myoliquefaction, unmarketable fish musculature due to unsightly macroscopic cysts, and reduced aquaculture production due to the outbreaks of neurological symptoms or cardiac diseases. Molecular genetic techniques have enabled the differentiation of Kudoa spp. with morphologically similar myxospores. In the present study, we employed integrated taxonomic approaches on five Kudoa spp. forming cysts between the trunk muscle myofibers (K. bora from Osteomugil perusii and K. lutjanus from Acanthopagrus latus), or cysts in the gallbladder wall (K. petala from Sillago sihama), and pseudocysts in the trunk muscle myofibers (K. uncinata from Nuchequula nuchalis and K. fujitai n. sp. from O. perusii). These four host fishes, which originated in the South China Sea, were purchased in the wet markets in Zhanjiang City, Guangdong Province, China, between August 2016 and April 2018. We have redescribed the four Kudoa spp. (K. bora, K. lutjanus, K. petala, and K. uncinata) on which little data are available after their original descriptions. Particularly, genetic characterization of K. bora and K. lutjanus, which are known to have myxospores morphologically similar to those of K. iwatai, was performed based on the nuclear ribosomal RNA gene and partial mitochondrial DNA genes such as cytochrome c oxidase subunit I and small and large ribosomal genes, demonstrating the validity and independence of these three kudoid species. We also provide description of a new species-K. fujitai n. sp.-in the present study. Application of integrated taxonomic approaches to known species characterized solely based on morphological criteria, as well as unknown species (e.g., K. fujitai n. sp. in the present study), contributes to better understanding of the biodiversity of Kudoa and multivalvulid myxosporeans.


Assuntos
Doenças dos Peixes/microbiologia , Myxozoa/classificação , Animais , Aquicultura , Biodiversidade , China , DNA Ribossômico , Tipagem Molecular , Myxozoa/isolamento & purificação , Filogenia , RNA Ribossômico 18S/genética , Análise de Sequência de DNA
13.
Int J Syst Evol Microbiol ; 70(4): 2732-2739, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32213249

RESUMO

A Gram-stain-negative, strictly aerobic, motile, rod-shaped bacterium with monopolar flagella, designated as MC042T, was isolated from the profound head ulcers of farmed Murray cod sampled from Zhejiang Province, China. Analysis of its 16S rRNA gene sequence and multilocus sequence analysis phylogeny showed that strain MC042T belonged to the genus Pseudomonas, showing the highest 16S rRNA gene sequence similarity to Pseudomonas juntendi BML3T (98.9 %), and less than 98.8 % similarity to other Pseudomonas species with validly published names. Whole-genome sequencing and phylogenetic reconstruction based on a core set of 1563 Pseudomonas genes further indicated that strain MC042T was most closely related to the clade formed by Pseudomonas protegens CHA0T and Pseudomonas saponiphila DSM 975T and distantly related to any of the validly published species of the genus Pseudomonas. Furthermore, strain MC042T could be distinguished from its closely related species of the genus Pseudomonas by its ability to assimilate maltose, d-xylose and melibiose, but not d-mannitol. The principal fatty acids were C16 : 0, summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1ω7c) and summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c). The respiratory quinone was Q-9. Polar lipids of strain MC042T comprised diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, unidentified glycolipids, an unidentified lipid, an unknown glycolipid and aminolipid. Based on its phenotypic, chemotaxonomic and phylogenetic features, strain MC042T is considered to represent a novel species, for which the name Pseudomonas piscis sp. nov. is proposed. The type strain is MC042T (=KCTC 72033T=MCCC 1K03575T).


Assuntos
Doenças dos Peixes/microbiologia , Perciformes/microbiologia , Filogenia , Pseudomonas/classificação , Úlcera/veterinária , Animais , Técnicas de Tipagem Bacteriana , Composição de Bases , China , DNA Bacteriano/genética , Ácidos Graxos/química , Glicolipídeos/química , Hibridização de Ácido Nucleico , Fosfolipídeos/química , Pseudomonas/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Úlcera/microbiologia , Vitamina K 2/análogos & derivados , Vitamina K 2/química
14.
Res Vet Sci ; 130: 212-221, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32203766

RESUMO

A trial was operated to assess the potential of using Lactobacillus plantarum L-137 (L-137) and/or ß-glucan (BG) in improving the resistance of Nile tilapia against Aeromonas hydrophila. Control diet and 3 diets supplemented with L-137, BG or L-137 + BG were prepared. Final body weight, specific growth rate, superoxide dismutase, and catalase showed considerably (P < .05) increased values in L-137 or L-137/BG groups, while glutathione peroxidase increased significantly (P < .05) only in L-137/BG group. Fish fed L-137 and/or BG diets showed that feed conversion ratio and malonaldehyde levels were significantly decreased (P < .05). Also, both L-137 and BG helped Nile tilapia to have high phagocytosis activity and relative expression of tumor necrosis factor-alpha (TNF-α) and interleukin 1 beta (IL-1ß) and interferon-gamma (INF-γ) genes. After A. hydrophila challenge, the intestinal villi epithelium of the L-137/BG group was intact and denser than the other groups. The hepatopancreas and spleen of the control group displayed severe necrosis in hepatocytes and congestion of blood sinusoids in addition to diffuse vacuolation. Regarding the L-137, BG and L-137/BG groups, there was a moderate and normal degree of vacuolation with focal necrosis and mild to moderate degree of congestion of blood sinusoids. Red blood cells, hemoglobin, and albumin showed meaningfully (P < .05) increased values in L-137 or L-137/BG groups. TNF-α, IL-1ß, and INF-γ expressions were upregulated by L-137 and/or BG. The obtained results revealed the ability of L-137 and/or BG to protect Nile tilapia from the effects of A. hydrophila infection by the motivation of the immune, antioxidative, and antiinflammation responses.


Assuntos
Adjuvantes Imunológicos/farmacologia , Aeromonas hydrophila/fisiologia , Doenças dos Peixes/tratamento farmacológico , Infecções por Bactérias Gram-Negativas/veterinária , Lactobacillus plantarum/química , Probióticos/farmacologia , beta-Glucanas/farmacologia , Adjuvantes Imunológicos/administração & dosagem , Ração Animal/análise , Animais , Antioxidantes/metabolismo , Dieta/veterinária , Resistência à Doença/imunologia , Doenças dos Peixes/microbiologia , Proteínas de Peixes/imunologia , Proteínas de Peixes/metabolismo , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Infecções por Bactérias Gram-Negativas/microbiologia , Probióticos/administração & dosagem , beta-Glucanas/administração & dosagem
15.
Vet Res ; 51(1): 45, 2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-32197655

RESUMO

Yersinia ruckeri is a facultative intracellular enterobacterium mostly known as the causative agent of enteric redmouth disease in salmonid fish. In the present study, we applied RNA inhibition to silence twenty pre-selected genes on the genome of a fish cell line (CHSE-214) followed by a gentamicin assay to quantify the effect of silencing on the cells' susceptibility to infection and found that silencing of 18 out of 20 genes significantly reduced the number of Y. ruckeri recovered. These findings improve our understanding of the infection process by Y. ruckeri and of the interactions between this bacterial pathogen and host cells.


Assuntos
Doenças dos Peixes/genética , Proteínas de Peixes/genética , Inativação Gênica , RNA Interferente Pequeno/genética , Yersiniose/veterinária , Animais , Linhagem Celular , Doenças dos Peixes/microbiologia , Proteínas de Peixes/metabolismo , RNA Interferente Pequeno/metabolismo , Yersiniose/genética , Yersiniose/microbiologia , Yersinia ruckeri/fisiologia
16.
J Fish Dis ; 43(5): 571-581, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32196698

RESUMO

Nocardia seriolae, a Gram-positive bacterium, is the main pathogen of fish nocardiosis. Protein NlpC/P60 is a cell-wall peptidase and a potential virulence factor of N. seriolae. Subcellular localization research revealed that both NlpC/P60-GFP and NlpC/P60Δsig-GFP fusion proteins were evenly distributed in the whole cell of fathead minnow (FHM) cells. Furthermore, typical apoptotic features, such as nuclear pyrosis and apoptotic bodies, were observed in the transfected FHM cells and grouper spleen cells by the overexpression of protein NlpC/P60. Then, quantitative assays of mitochondrial membrane potential (ΔΨm) value, caspase-3 activity and apoptosis-related gene (Bax, BNIP3, TNF1 and TNF6) mRNA expression were conducted. The results showed that ΔΨm was decreased, caspase-3 was significantly activated, and the mRNA expression of pro-apoptotic genes (Bax and BNIP3) and tumour necrosis factors (TNF1 and TNF6) was up-regulated in NlpC/P60-overexpressed cells. Taken together, the results indicated that the protein NlpC/P60 of N. seriolae might involve in apoptosis regulation. This study may lay the foundation for further study on the function of N. seriolae NlpC/P60 and promote the understanding of the virulence factors and pathogenic mechanism of N. seriolae.


Assuntos
Apoptose , Proteínas de Bactérias/genética , Cyprinidae , Nocardia/genética , Peptídeo Hidrolases/genética , Fatores de Virulência/genética , Sequência de Aminoácidos , Animais , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Parede Celular/metabolismo , Doenças dos Peixes/microbiologia , Nocardia/enzimologia , Nocardiose/microbiologia , Nocardiose/veterinária , Peptídeo Hidrolases/química , Peptídeo Hidrolases/metabolismo , Filogenia , Alinhamento de Sequência , Fatores de Virulência/química , Fatores de Virulência/metabolismo
17.
J Fish Dis ; 43(5): 561-570, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32196708

RESUMO

Flavobacterium psychrophilum is the causative agent of bacterial cold-water disease and rainbow trout syndrome in freshwater salmonid fish worldwide, generating injuries and high mortality rates. Despite several studies on this bacterium, the infection mechanism remains unknown due to limitations in the employed animal models. In this work, we propose using zebrafish (Danio rerio) as a model for studying bacterial pathogenicity. To substantiate this proposal, zebrafish infection by F. psychrophilum strain JIP 02/86 was characterized. Zebrafish larvae were infected using the bath method, and morphological changes and innate immune system activation were monitored using transgenic fish. Salmonid-like infection phenotypes were observed in 4.74% of treated larvae, as manifested by fin, muscle and caudal peduncle damage. Symptomatic and dead larvae accounted for 1.35% of all challenged larvae. Interestingly, infected larvae with no infection phenotypes showed stronger innate immune system activation than specimens with phenotypes. A failure of function assay for myeloid factor pu.1 resulted in more infected larvae (up to 43.5%), suggesting that low infection rates by F. psychrophilum would be due to the protective actions of the innate immune system against this bacterium in zebrafish larvae. Our results support the use of zebrafish as an infection model for studying F. psychrophilum. Furthermore, the percentage of infected fish can be modulated by disturbing, to varying extents, the differentiation of myeloid cells. Using this evidence as a starting point, different aspects of the infection mechanism of F. psychrophilum could be studied in vivo.


Assuntos
Modelos Animais de Doenças , Doenças dos Peixes/microbiologia , Infecções por Flavobacteriaceae/veterinária , Flavobacterium/fisiologia , Peixe-Zebra , Animais , Infecções por Flavobacteriaceae/microbiologia
18.
Lett Appl Microbiol ; 70(6): 431-439, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32031273

RESUMO

This study was performed to evaluate the effects of dietary probiotics on growth, non-specific immune responses and disease resistance in olive flounder, Paralichthys olivaceus. During 8 weeks, the fish were fed the five experimental diets such as a basal commercial diet (CON), oxytetracycline (OTC) and three basal diets containing Bacillus subtilis (BS), a commercial microbial product (CES) and a mixture of yeast and bacterium (PI), respectively. Fish fed all the probiotics diets and OTC showed a significantly higher growth than fish-fed CON (P < 0·05). Fish-fed PI had a significantly higher nitroblue tetrazolium activity, whereas fish-fed CES showed a higher lysozyme level (P < 0·05). A 7-day challenge test also showed that fish-fed PI had a cumulative survival rate equivalent to that of fish-fed OTC (P < 0·05). Moreover, the diet (PI) appeared to increase the diversity of microbial community in the fish. All these results suggest that the probiotics diet could function as a potential antibiotic replacer in the olive flounder. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is unique in revealing that a diet mixture of yeast, Groenewaldozyma salmanticensis and bacterium Gluconacetobacter liquefaciens can enhance growth, innate immunity and diversity of microbial community including dominant species in the olive flounder. All these indicate that the diet mixture could function as a potential antibiotic replacer in one of the most commercially important fisheries in South Korea.


Assuntos
Ração Animal/microbiologia , Linguado/crescimento & desenvolvimento , Linguado/imunologia , Gluconacetobacter/fisiologia , Probióticos/farmacologia , Saccharomycetales/fisiologia , Ração Animal/análise , Animais , Bacillus subtilis/fisiologia , Dieta , Resistência à Doença/fisiologia , Doenças dos Peixes/microbiologia , Linguado/microbiologia , República da Coreia
19.
Microb Genom ; 6(2)2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32108566

RESUMO

Edwardsiella ictaluri and Edwardsiella piscicida are important fish pathogens affecting cultured and wild fish worldwide. To investigate the genome-level differences and similarities between catfish-adapted strains in these two species, the complete E. ictaluri 93-146 and E. piscicida C07-087 genomes were evaluated by applying comparative genomics analysis. All available complete (10) and non-complete (19) genomes from five Edwardsiella species were also included in a systematic analysis. Average nucleotide identity and core-genome phylogenetic tree analyses indicated that the five Edwardsiella species were separated from each other. Pan-/core-genome analyses for the 29 strains from the five species showed that genus Edwardsiella members have 9474 genes in their pan genome, while the core genome consists of 1421 genes. Orthology cluster analysis showed that E. ictaluri and E. piscicida genomes have the greatest number of shared clusters. However, E. ictaluri and E. piscicida also have unique features; for example, the E. ictaluri genome encodes urease enzymes and cytochrome o ubiquinol oxidase subunits, whereas E. piscicida genomes encode tetrathionate reductase operons, capsular polysaccharide synthesis enzymes and vibrioferrin-related genes. Additionally, we report for what is believed to be the first time that E. ictaluri 93-146 and three other E. ictaluri genomes encode a type IV secretion system (T4SS), whereas none of the E. piscicida genomes encode this system. Additionally, the E. piscicida C07-087 genome encodes two different type VI secretion systems. E. ictaluri genomes tend to encode more insertion elements, phage regions and genomic islands than E. piscicida. We speculate that the T4SS could contribute to the increased number of mobilome elements in E. ictaluri compared to E. piscicida. Two of the E. piscicida genomes encode full CRISPR-Cas regions, whereas none of the E. ictaluri genomes encode Cas proteins. Overall, comparison of the E. ictaluri and E. piscicida genomes reveals unique features and provides new insights on pathogenicity that may reflect the host adaptation of the two species.


Assuntos
Edwardsiella ictaluri/genética , Edwardsiella/genética , Infecções por Enterobacteriaceae/veterinária , Doenças dos Peixes/microbiologia , Genoma Bacteriano , Animais , Peixes-Gato/microbiologia , Edwardsiella/isolamento & purificação , Edwardsiella/metabolismo , Edwardsiella ictaluri/isolamento & purificação , Edwardsiella ictaluri/metabolismo , Infecções por Enterobacteriaceae/microbiologia , Genômica , Filogenia
20.
BMC Vet Res ; 16(1): 40, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32013968

RESUMO

BACKGROUND: Renibacterium salmoninarum and Mycobacterium sp. are important bacterial pathogens of fish. R. salmoninarum is the causative agent of bacterial kidney disease, a Gram-positive bacterium mostly known for causing chronic infections in salmonid fish, while multiple species belonging to the Mycobacterium genus have been associated with mycobacteriosis in fish as well as in human. The objective of this study was to determine the prevalence of these two bacterial pathogens in populations of wild brown trout (Salmo trutta fario) in four rivers (Kamp, Wulka, Traun and Ybbs) in Austria. RESULTS: A total of 457 kidney samples were examined for both bacterial agents using nested and conventional PCR as well as bacterial cultivation on KDM-2, histological examination and immunohistochemistry. Molecular evidence showed an estimated prevalence level of 0.94% for R. salmoninarum in 2017 while the bacterium could not be detected in 2018 and histology showed signs consistent with a low-level chronic inflammation in the kidney of infected fish. Similarly, no fish were found positive for Mycobacterium in 2017 but in 2018, the prevalence was found to be 37.03% in the Kamp river (4.08% across all rivers). The sequencing data confirmed that these fish carried Mycobacterium sp. although the precise species of Mycobacterium could not be ascertained. CONCLUSIONS: This survey constitutes the first insight into the prevalence rate of R. salmoninarum and Mycobacterium sp. in wild brown trout (Salmo trutta fario) populations in Austria. Both of these pathogens were only detected in the summer months (June and July), which might suggest that the stress linked to increased water temperature could act as stressor factor and contribute to the outbreak of these diseases. The age of the fish might also play a role, especially in the case of Mycobacterium sp. as all the infected fish were in their first summer (June).


Assuntos
Doenças dos Peixes/microbiologia , Micrococcaceae/isolamento & purificação , Mycobacterium/isolamento & purificação , Infecções por Actinomycetales/epidemiologia , Infecções por Actinomycetales/veterinária , Animais , Áustria/epidemiologia , Doenças dos Peixes/epidemiologia , Nefropatias/epidemiologia , Nefropatias/microbiologia , Nefropatias/veterinária , Infecções por Mycobacterium/epidemiologia , Infecções por Mycobacterium/veterinária , Reação em Cadeia da Polimerase/veterinária , Estações do Ano , Truta/microbiologia
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