• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5
  • 2
  • 1
  • 1
  • Tagged with
  • 9
  • 9
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Estudo da Columnariose de quatro espécies de peixes tropicais: isolamento e caracterização de Flavobacterium columnare.

Pilarski, Fabiana 24 May 2002 (has links)
Piracanjubas (Brycon orbignyanus), Pacus (Piaractus mesopotamicus), Tambaquis (Colossoma macropomum) e Cascudos (Hypostomus plecostomus) oriundos de criatórios do CEPTA/IBAMA atendidos pelo Laboratório de Sanidade de Peixes, foram diagnosticados como acometidos clinicamente de columnariose através de lesões características na região dorsal, caudal e brânquias dos peixes. Através de raspado das lesões e montagem a fresco em lâmina de microscopia, evidenciou-se a presença de bacilos típicos de Flavobacterium columnare (Flexibacter columnaris). Esfregaços corados com azul de metileno evidenciaram bacilos finos, arranjados em forma de colunas corados em azul. Das áreas lesadas, foi coletado através de swab estéril material para o isolamento microbiológico em meios de cultura artificiais (líquido e sólido) próprios para o estudo de Flavobacterium sp. (segundo Carlson & Pacha, 1968). No meio líquido houve o desenvolvimento de microrganismos que, observados em gota pendente apresentaram a forma de bacilos finos, longos, móveis por deslizamento. Através da coloração de Gram apresentaram morfologia de bacilos finos, gram negativos, agrupados em colunas. O plaqueamento em meio sólido desenvolveu colônias pequenas, cinza-amareladas, com bordo em forma de raiz. Foi realizada a caracterização bioquímica das amostras. Deste modo caracterizamos as quatro cepas isoladas como sendo do gênero Flavobacterium columnare. / Four Flavobacterium columnare strains were isolated from piracanjubas (Brycon orbignyanus), pacus (Piaractus mesopotamicus), tambaquis (Colossoma macropomum) and cascudos (Hypostomus plecostomus), showing disease signs in the back, caudal fin and gills. The fish were obtained from different ponds at the National Center of Researches of Tropical Fish (CEPTA/IBAMA – Brazil). Samples for culture were obtained by skin scrapes of moribund fishes and was detected by wet mount using phase contrast microscope for the presence of Flavobacterium columnare. Sterile cotton swabs from the skin and gills were taken and streaked onto artificial culture medium (broth and agar) which is used for the isolation of Flavobacterium columnare. The bacterial cells of all strains in the broth cultures were gram negative, long, filamentous, exhibiting flexing movements (gliding motility) and gathered into 'columns'. Strains in the agar produced yellow-gray colonies, rather small, flat and had rhizoid edges. Biochemical characterization proved that the isolated strains could be classified as Flavobacterium columnare.
2

Estudo da Columnariose de quatro espécies de peixes tropicais: isolamento e caracterização de Flavobacterium columnare.

Fabiana Pilarski 24 May 2002 (has links)
Piracanjubas (Brycon orbignyanus), Pacus (Piaractus mesopotamicus), Tambaquis (Colossoma macropomum) e Cascudos (Hypostomus plecostomus) oriundos de criatórios do CEPTA/IBAMA atendidos pelo Laboratório de Sanidade de Peixes, foram diagnosticados como acometidos clinicamente de columnariose através de lesões características na região dorsal, caudal e brânquias dos peixes. Através de raspado das lesões e montagem a fresco em lâmina de microscopia, evidenciou-se a presença de bacilos típicos de Flavobacterium columnare (Flexibacter columnaris). Esfregaços corados com azul de metileno evidenciaram bacilos finos, arranjados em forma de colunas corados em azul. Das áreas lesadas, foi coletado através de swab estéril material para o isolamento microbiológico em meios de cultura artificiais (líquido e sólido) próprios para o estudo de Flavobacterium sp. (segundo Carlson & Pacha, 1968). No meio líquido houve o desenvolvimento de microrganismos que, observados em gota pendente apresentaram a forma de bacilos finos, longos, móveis por deslizamento. Através da coloração de Gram apresentaram morfologia de bacilos finos, gram negativos, agrupados em colunas. O plaqueamento em meio sólido desenvolveu colônias pequenas, cinza-amareladas, com bordo em forma de raiz. Foi realizada a caracterização bioquímica das amostras. Deste modo caracterizamos as quatro cepas isoladas como sendo do gênero Flavobacterium columnare. / Four Flavobacterium columnare strains were isolated from piracanjubas (Brycon orbignyanus), pacus (Piaractus mesopotamicus), tambaquis (Colossoma macropomum) and cascudos (Hypostomus plecostomus), showing disease signs in the back, caudal fin and gills. The fish were obtained from different ponds at the National Center of Researches of Tropical Fish (CEPTA/IBAMA – Brazil). Samples for culture were obtained by skin scrapes of moribund fishes and was detected by wet mount using phase contrast microscope for the presence of Flavobacterium columnare. Sterile cotton swabs from the skin and gills were taken and streaked onto artificial culture medium (broth and agar) which is used for the isolation of Flavobacterium columnare. The bacterial cells of all strains in the broth cultures were gram negative, long, filamentous, exhibiting flexing movements (gliding motility) and gathered into 'columns'. Strains in the agar produced yellow-gray colonies, rather small, flat and had rhizoid edges. Biochemical characterization proved that the isolated strains could be classified as Flavobacterium columnare.
3

Suplementação dietética de selênio e vitamina E: variáveis fisiológicas e desempenho de juvenis de pacu (Piaractus mesopotamicus)

Gimbo, Rodrigo Yukihiro [UNESP] 21 February 2011 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:23:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-21Bitstream added on 2014-06-13T20:49:59Z : No. of bitstreams: 1 gimbo_ry_me_jabo.pdf: 307503 bytes, checksum: 530b1418c873f8324ea4137e8179df61 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Já é de conhecimento que tanto o selênio quanto a vitamina E possuem capacidades imunoestimulante, separadamente. Entretanto, pouco se sabe sobre a interação desses dois ingredientes em respostas biológicas de juvenis de pacu (Piaractus mesopotamicus). Assim, o objetivo deste trabalho foi avaliar as respostas fisiológicas, imunológicas e zootécnicas desta espécie à administração oral de três níveis de selênio (0; 0,6 e 1,2 mg.kg-1), três níveis de vitamina E (0; 200 e 400 mg.kg-1) e o perfil destas respostas antes e após o desafio com Aeromonas hydrophila). O estudo formou assim, um fatorial 3x3x2, distribuído em delineamento inteiramente casualizado com quatro repetições. Em cada amostragem foram coletados, aleatóriamente, dois peixes de cada aquário para a biometria, coleta de sangue via punção da veia caudal e injeção intraperitoneal de Aeromonas nos peixes restantes. Com os dados da biometria, foram avaliados o ganho de peso, taxa de crescimento específico (TCE) e fator de condição. No sangue, foram determinados o hematócrito, número de eritrócitos, trombócitos e leucócitos, volume corpuscular médio (VCM), concentração de hemoglobinaatividade respiratória de leucócitos, glicemia, proteínas totais, albumina e também foi estimado o valor de globulinas. O nível de 0,6 mg.kg-1 de selênio promoveu o melhor ganho de peso e TCE. A atividade respiratória de leucócitos, número de leucócitos e trombócitos reduziram após o desafio. A inclusão de 1,2 mg.kg-1 de selênio está relacionada com o aumento de proteínas totais e globulinas, independente da concentração de vitamina E, enquanto a deficiência de selênio resultou no aumento da glicemia. O número de eritrócitos sofreu influência tanto dos níveis de selênio como dos níveis de vitaminas E... / The immunostimulant capacity of selenium and of vitamin E is known. However, little is known about the interaction of these two ingredients on biological responses of pacu (Piaractus mesopotamicus) juvenile. Thus, the purpose of this study was to evaluate the physiological, immunological and productive performance of this fish to the oral administration of three levels of selenium (0, 0.6 and 1.2 mg.kg-1), three levels of vitamin E (0, 200 and 400 mg.kg-1) and the profile of these responses before and after challenge with Aeromonas hydrophila). The study formed then a 3x3x2 factorial design, distributed in a randomized design with four replications. In each sample were collected randomly, two fish from each aquarium for biometrics, blood was collected via caudal vein puncture and intraperitoneal injection of Aeromonas in fish remaining. With biometric data, we assessed weight gain, specific growth rate (SGR) and condition factor. Blood was used to determine hematocrit, erythrocytes, thrombocytes and leukocytes count, mean corpuscular volume (MCV), hemoglobin concentration, respiratory activity of leukocytes, blood glucose, total protein, albumin, and globulins concentration was estimated. The level of 0.6 mg.kg-1 of selenium had the best average for weight gain and TBI. Respiratory activity of leukocytes, leukocytes and thrombocytes count decreased after challenge. The inclusion of 1.2 mg.kg-1 of selenium are related to the total protein and globulin increase , independent of the concentration of vitamin E, while selenium deficiency resulted in increased blood glucose. The number of erythrocytes was influenced both the levels of selenium and vitamin E levels, the other hematological variables were observed only effect of selenium. The inclusion of 1.2 mg.kg-1 of selenium and 200 mg.kg-1 of vitamin E in the diet of juvenile pacu was satisfactory for growth and immunity of fish
4

Suplementação dietética de selênio e vitamina E : variáveis fisiológicas e desempenho de juvenis de pacu (Piaractus mesopotamicus) /

Junqueira, Juliana Bega. January 2011 (has links)
Orientador: Elisabeth Criscuolo Urbinati / Banca: Leonardo Susumu Takahashi / Banca: Fabiana Pilarski / Resumo: Já é de conhecimento que tanto o selênio quanto a vitamina E possuem capacidades imunoestimulante, separadamente. Entretanto, pouco se sabe sobre a interação desses dois ingredientes em respostas biológicas de juvenis de pacu (Piaractus mesopotamicus). Assim, o objetivo deste trabalho foi avaliar as respostas fisiológicas, imunológicas e zootécnicas desta espécie à administração oral de três níveis de selênio (0; 0,6 e 1,2 mg.kg-1), três níveis de vitamina E (0; 200 e 400 mg.kg-1) e o perfil destas respostas antes e após o desafio com Aeromonas hydrophila). O estudo formou assim, um fatorial 3x3x2, distribuído em delineamento inteiramente casualizado com quatro repetições. Em cada amostragem foram coletados, aleatóriamente, dois peixes de cada aquário para a biometria, coleta de sangue via punção da veia caudal e injeção intraperitoneal de Aeromonas nos peixes restantes. Com os dados da biometria, foram avaliados o ganho de peso, taxa de crescimento específico (TCE) e fator de condição. No sangue, foram determinados o hematócrito, número de eritrócitos, trombócitos e leucócitos, volume corpuscular médio (VCM), concentração de hemoglobinaatividade respiratória de leucócitos, glicemia, proteínas totais, albumina e também foi estimado o valor de globulinas. O nível de 0,6 mg.kg-1 de selênio promoveu o melhor ganho de peso e TCE. A atividade respiratória de leucócitos, número de leucócitos e trombócitos reduziram após o desafio. A inclusão de 1,2 mg.kg-1 de selênio está relacionada com o aumento de proteínas totais e globulinas, independente da concentração de vitamina E, enquanto a deficiência de selênio resultou no aumento da glicemia. O número de eritrócitos sofreu influência tanto dos níveis de selênio como dos níveis de vitaminas E... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The immunostimulant capacity of selenium and of vitamin E is known. However, little is known about the interaction of these two ingredients on biological responses of pacu (Piaractus mesopotamicus) juvenile. Thus, the purpose of this study was to evaluate the physiological, immunological and productive performance of this fish to the oral administration of three levels of selenium (0, 0.6 and 1.2 mg.kg-1), three levels of vitamin E (0, 200 and 400 mg.kg-1) and the profile of these responses before and after challenge with Aeromonas hydrophila). The study formed then a 3x3x2 factorial design, distributed in a randomized design with four replications. In each sample were collected randomly, two fish from each aquarium for biometrics, blood was collected via caudal vein puncture and intraperitoneal injection of Aeromonas in fish remaining. With biometric data, we assessed weight gain, specific growth rate (SGR) and condition factor. Blood was used to determine hematocrit, erythrocytes, thrombocytes and leukocytes count, mean corpuscular volume (MCV), hemoglobin concentration, respiratory activity of leukocytes, blood glucose, total protein, albumin, and globulins concentration was estimated. The level of 0.6 mg.kg-1 of selenium had the best average for weight gain and TBI. Respiratory activity of leukocytes, leukocytes and thrombocytes count decreased after challenge. The inclusion of 1.2 mg.kg-1 of selenium are related to the total protein and globulin increase , independent of the concentration of vitamin E, while selenium deficiency resulted in increased blood glucose. The number of erythrocytes was influenced both the levels of selenium and vitamin E levels, the other hematological variables were observed only effect of selenium. The inclusion of 1.2 mg.kg-1 of selenium and 200 mg.kg-1 of vitamin E in the diet of juvenile pacu was satisfactory for growth and immunity of fish / Mestre
5

The effect of environmental factors and hormone treatments on ovulation rate and spawning success in cardinal tetras, Paracheirodon axelrodi (Pisces: Characidae)

Burton, Simon Mark January 1998 (has links)
Cardinal tetras, Paracheirodon axelrodi (Pisces: Characidae), are among the most popular tropical ornamental fish in the world. Millions of cardinal tetras are removed from their natural habitat, the upper tributaries of the Rio Negro in Brazil, each year and exported to North America and Europe where they are abundantly available at low cost. This, combined with the fact that they do not spawn freely in captivity has excluded any incentive to culture this fish on a commercial scale in these areas. However, the demand for cardinal tetras in South Africa is high, but their availability is limited to sporadic imports of wild caught fish which has resulted in an increase in their relative value. Thus, there is an appreciable incentive to investigate methods for inducing this species to reproduce in captivity. Information on methods for inducing spawning would form an integral part of a potential production plan for the culture of this species in South Africa. This study consisted of a number of experiments designed to investigate factors related to the spawning of cardinal tetras in captivity. The first series of experiments investigated the effect of variables such as the water chemistry of the experimental system, the sex ratio of the fish, the effect of conditioning and the effect of different spawning media on spawning success. The second series of experiments tested the effects of various environmental stimuli or hormonal treatments on spawning in cardinal tetras. Environmental stimuli tested included a rise in temperature, a rise in water level and a fresh rain water flush. Hormonal treatments included feeding GnRHa enriched brine shrimps to the fish or the application of hormone injections (hypophysation). Neither environmental stimuli nor brine shrimp enrichment induced cardinals to spawn in a repeatable manner. The same was true for hypophysation, but in this case a low incedence of ovulation of injected females was observed. Oocytes from ovulated and non-ovulated females were examined under a microscope and from this it was determined that cardinal tetras are group synchronous spawners, containing two distinct cohorts of oocytes in the ovary. The effect of a number of environmental stimuli on ovulation rate in cardinal tetras were then tested but did not induce ovulation in any females. A series of three experiments was performed investigating the effect of conditioning the sexes together on ovulation rate and spawning success. Conditioning the sexes together had no effect on spawning success, but a significantly higher ovulation rate was observed in females that vvere conditioned together with males. Male cardinals did not follow this trend and lost condition when conditioned together with females. The next experiment tested if pheromones from red serpae tetras, Hyphessobrycon serpae, could be used to induce ovulation and spawning in cardinal tetras. This was found not to be the case. The final series of experiments tested the effect of Aquaspawn® enriched Artemia on ovulation rates in female cardinal tetras. Aquaspawn® is a water soluble preparation of GnRHa and dopamine. Aquaspawn® enriched Artemia were found to be effective for inducing female cardinal tetras to ovulate. However, the results from this method of enrichment were not entirely reliable and further research is warranted. Finally, a protocol for evaluating spawning in topical, freshwater egg-laying fish was proposed, based on the results from this study. The advantages and disadvantages of such a protocol were discussed.
6

Studies on the host range and chemical control of fungi associated with diseased tropical fish

Warren, Charles Ophus January 1963 (has links)
Collections of Saprolegniaceous fungi were made from diseased tropical fish. Nineteen strains, representing three fungal genera (<u>Saprolegnia</u>, <u>Achlya</u> and <u>Pythium</u>), were isolated from 11 fish species. Due to difficulty in inducing sexual fruiting, only two strains were identified to species; both of these being <u>A. americana</u>. Laboratory infection studies revealed the ability of strains of each different fungus to infect five selected tropical fish species. <u>Saprolegnia</u> sp. and <u>A. americana</u> proved to be more vigorous and lethal pathogens than <u>Pythium</u> sp. No indications of host specificity were evident. All chemicals tested (Table 4) showed definite fungicidal abilities. No effective fungicidal concentration of the chemicals tested would permit sustained fish culturing. Malachite green was the most effective fungicide tested, being functional in concentrations as low as 2 ppm. / Master of Science
7

Processamento de Piraiba (Brachyplatystoma Filamentosum) : desidratação osmotica, defumação e secagem / Processing of Piraiba (Brachyplatystoma Filamentosum) : osmotic dehydration, smoking and drying

Ribeiro, Carmelita de Fatima Amaral 14 August 2018 (has links)
Orientadores: Kil Jin Park, Miriam Dupas Hubinger / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-14T17:46:45Z (GMT). No. of bitstreams: 1 Ribeiro_CarmelitadeFatimaAmaral_D.pdf: 5143469 bytes, checksum: fdc1326e9adc959546e6613313358756 (MD5) Previous issue date: 2009 / Resumo: O presente trabalho teve como objetivo estudar os efeitos de dois tratamentos de desidratação osmótica usando concentrações molares de NaCl e os processos de defumação líquida e posterior secagem da piraíba. O processo de desidratação osmótica foi estudado para verificar a influência dos fatores temperatura, concentração molar de NaCl e tempo de processo, nas respostas, perda de peso, perda de água e ganho de sal. No primeiro tratamento, foi utilizado um planejamento fatorial completo de 23 totalizando 17 ensaios, tendo como variáveis independentes a temperatura (22-38°C), concentração molar (0,03-0,37 mol/L) e tempo de processo (199-401 min). No segundo tratamento foi utilizado um planejamento fatorial de 23 totalizando 11 ensaios, tendo como variáveis independentes a temperatura (35-45°C), concentração molar (0,7-0,9 mol/L) e tempo de processo (90-150 min). Com relação aos tratamentos aplicados na desidratação osmótica, a temperatura e concentração molar, foram os fatores que apresentaram maior influência sobre as respostas de perda de água e ganho de sal. O processo de defumação líquida foi estudado através de um planejamento fatorial de 23 com quatro repetições no ponto central. As variáveis avaliadas foram temperatura de secagem (40-60°C), concentração da solução de aroma de fumaça (20-30% p/p) e tempo de imersão (20-30s), tendo como resposta a difusividade efetiva. A secagem foi realizada em secador convectivo onde foi mantida uma única velocidade do ar (1,08m/s). O ajuste dos dados experimentais obtidos na secagem de piraíba (in natura e defumada) foi realizado utilizando-se o modelo teórico de Fick e os modelos empíricos de Midilli et al., Page, Wang e Singh e Henderson e Pabis, para geometria cúbica. Os valores da difusividade efetiva variaram de 2,39x10-10 a 8,54x10-10 m2/s. Os modelos de Midilli et al. e Page apresentaram melhor ajuste em relação aos outros modelos. A avaliação do produto final e matéria prima foi realizada através de análises de atividade de água, umidade, cinzas, proteínas, lipídios, pH e cloretos. Foram encontrados baixos valores de umidade, pH e atividade de água nas amostras obtidas no segundo tratamento de desidratação osmótica. As amostras defumadas apresentaram teor de cinzas e cloretos elevados, além de baixos teores de lipídios. A matéria prima e o produto final defumado foram analisados microbiologicamente de acordo com a legislação vigente, estando em conformidade com os parâmetros exigidos. Foi realizada análise sensorial de aceitação de kibe de peixe defumado, a qual não houve diferença significativa, a p_0,05, entre as amostras defumadas e a amostra padrão com relação aos atributos aroma, sabor, teor de sal, textura e impressão global. / Abstract: The objective of this research work was to study the effects of two osmotic dehydration treatments employing molar concentrations of NaCl as well as liquid smoking followed by piraíba samples drying. Osmotic drying process was studied to take into account factors as temperature, NaCl concentration and processing time on weight loss, water loss and salt gain. For the first treatment it was adopted a Complete Factorial of 23 Model totalizing 17 trials, selecting temperature (22-38°C), molar concentration (0,03-0,37 mol/L) and processing time (199-401 min) as independents variables. In the second case a Complete Factorial of 23 Model totalizing 11 trials was also adopted holding the temperature (35-45°C), molar concentration (0,7-0,9 mol/L) and processing time (90-150 min) as independent variables. Temperature and molar concentration were noted to be the factors which most affect water loss and salt gain. liquid smoking process was studied by means of Factorial Model of 23 with four replications at the central point. Variables under consideration included drying temperature (40-60°C), smoke flavor concentration (20-30% p/p) and immersion time (20-30s), yielding effective diffusivity values as answer. Drying process was carried in a convective dryer keeping a constant air speed (1,08m/s). Experimental piraíba natural and smoked drying date were adjusted by means of the Fick theoretical model as well as by means of the Midilli et al., Page, Wang and Singh e Henderson and Pabis empiric models for the cubic geometry. Effective diffusivity values varied from 2,39x10-10 to 8,54x10-10 m2/s. Midilli et al. and Page Models presented the best adjustment as compared with other models. Final product evaluation as well as of raw material were carried by means of, water activity, humidity, ashes, lipids, proteins, pH and chlorides. Low pH and humidity values were found in the samples submitted to the second treatment of osmotic dehydration. Smoked samples presented high ash and chloride content and low lipid content. Raw material and final smoked product were submitted to microbiological analysis according to the legal code and found to agree with required parameters. The sensorial analysis indicated no significant difference at the level of p_0,05 smoked fish kibe between smoked samples and regular samples in respect to the attributes of flavor, taste, texture and general impressions. / Doutorado / Tecnologia Pós-Colheita / Doutor em Engenharia Agrícola
8

Ecosystèmes microbiens des poissons tropicaux après abattage et incidence sur la salubrité des produits. / Microbial ecosystem of tropical fish, thunnus albacares and sciaenops ocellatus, post mortem and impact on the quality of the products

Dauchy, Adèle 08 December 2016 (has links)
Le poisson est un produit très périssable dont l’altération résulte essentiellement de la croissance bactérienne. Comparé aux régions tempérées, peu d’études portent sur le microbiote d’altération des poissons tropicaux. En Martinique, le thon jaune (Thunnus albacares) et l’ombrine ocellée (Sciaenops ocellatus) représentent des poissons d’intérêt pour les filières pêche et aquaculture. Dans le but de mieux connaître le microbiote d’altération de ces poissons, des analyses culturales et aculturales (séquençage de nouvelle génération des amplicons d’ARNr 16S, Illumina MiSeq) ont été réalisées.Une grande diversité d’espèces bactériennes a été retrouvée dans le thon et l’ombrine fraîchement pêchés (104 et 887 OTUs, respectivement) et la plupart d’entre elles sont communément isolées des poissons (Chryseobacterium, Burkholderia, Flavobacterium, Psychrobacter, Arthrobacter, Staphylococcus). Certaines, comme Ralstonia sp. et Rhodanobacter terrae, en quantité importante dans le thon frais, sont plus atypiques. Au cours de l’entreposage du thon sous-glace, Pseudomonas et Brochothrix deviennent dominants. L’emballage sous atmosphère modifiée (MAP) ou sous vide (VP) entraine clairement la sélection de Brochothrix dans un cas et d’un mélange de Brochothrix, bactéries lactiques (Lactococcus piscium, Carnobacterium maltaromaticum) et d’entérobactéries (Hafnia paralvei) dans l’autre, et ne permet pas une augmentation significative de la durée de conservation. Pour les filets d’ombrine, peu de différences sont observées entre MAP et VP dont le microbiote se compose essentiellement de bactéries lactiques (Carnobacterium spp., Vagococcus spp., Lactococcus spp., Leuconostoc spp.). La durée de conservation est étendue de 15 jours par rapport au poisson entier sous air.L’inoculation de différentes espèces bactériennes dans de la chair pauci-microbienne de thon ou d’ombrine a montré que Hafnia paralvei et Serratia spp. sont les espèces les plus altérantes. Brochothrix thermosphacta et Carnobacterium spp. produisent aussi des odeurs indésirables mais de façon plus modérée. Chez Pseudomonas, les espèces ne sont pas toutes altérantes et présentent même parfois des capacités à empêcher le développement des mauvaises odeurs induites par d’autres bactéries (Pseudomonas psychrophila/fragi) et à dégrader l’histamine (Pseudomonas cedrina, Pseudomonas plecoglossicida/monteilii). En parallèle, des tests sensoriels et des dosages physico-chimiques ont également été réalisés pour comprendre les conséquences de la croissance bactérienne et identifier des indicateurs fiables pour l’évaluation du degré d’altération des produits. / Fish is a highly perishable product and spoilage is mainly due to the bacterial growth. Compared to temperate regions, few studies examined the spoilage microbiota of tropical fish. In Martinique, yellowfin tuna (Thunnus albacares) and red drum (Sciaenops ocellatus) are essential fish of fisheries and aquaculture sectors. For a better characterization of the microbial ecosystem, culture-dependent and culture-independent (next-generation sequencing of 16S rRNA amplicons, Illumina MiSeq) methods were carried out.A wide diversity of species was found in freshly caught tuna and red drum (104 and 887 OTUs, respectively) and most of them are commonly isolated from fish (Chryseobacterium, Burkholderia, Flavobacterium, Psychrobacter, Arthrobacter, Staphylococcus). Others, such as Ralstonia sp. and Rhodanobacter terrae, largely present in fresh tuna, are less familiar. During the ice-storage of tuna, Pseudomonas and Brochothrix became dominant. The modified atmosphere packaging (MAP) and vacuum packaging (VP) clearly leaded to the selection of Brochothrix in one case and to a mixture of Brochothrix, lactic acid bacteria (Lactococcus piscium, Carnobacterium maltaromaticum) and enterobacteria (Hafnia paralvei) in the other case, and not conduct to a significant increase of the shelf-life. For red drum fillets, few differences were observed between MAP and VP with a microbiota essentially composed by lactic acid bacteria (Carnobacterium spp., Vagococcus spp., Lactococcus spp., Leuconostoc spp.). The shelf-life was extended by 15 days compared to the whole fish ice-stored.The inoculation of different bacterial species into the pauci-microbial flesh of tuna or red drum showed that Hafnia paralvei and Serratia spp. were the most spoiling bacteria. Brochothrix thermosphacta and Carnobacterium spp. produced more moderate undesirable odors. Among the Pseudomonas genus, not all species induced spoiling effects and some of them are even able to prevent the development of unpleasant odors from other bacteria (Pseudomonas psychrophila/fragi) and to degrade histamine (Pseudomonas cedrina, Pseudomonas plecoglossicida/monteilii).At the same time, sensory tests and physico-chemical assays were performed to understand the consequences of the bacterial growth and to identify reliable indices for the evaluation of the spoilage degree of the products.
9

Impacts of Water Warming on the Physiology and Life-History of a Tropical Freshwater Fish

Brodnik, Reed Michael 13 August 2015 (has links)
No description available.

Page generated in 0.0833 seconds