• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 58
  • 15
  • 8
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 2
  • 2
  • 2
  • Tagged with
  • 97
  • 65
  • 14
  • 13
  • 13
  • 11
  • 10
  • 10
  • 9
  • 9
  • 9
  • 9
  • 8
  • 8
  • 8
  • 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.
51

Avaliação de desempenho da Anomalocardia brasiliana e Gracilaria sp. como biofiltros de efluente de camarão

SANTOS, Tereza Cristina Paiva dos 03 August 2009 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2017-02-22T13:46:48Z No. of bitstreams: 1 Tereza Cristina Paiva dos Santos.pdf: 917048 bytes, checksum: 524bf85d8e8ff4c8c945badbe9d99945 (MD5) / Made available in DSpace on 2017-02-22T13:46:48Z (GMT). No. of bitstreams: 1 Tereza Cristina Paiva dos Santos.pdf: 917048 bytes, checksum: 524bf85d8e8ff4c8c945badbe9d99945 (MD5) Previous issue date: 2009-08-03 / The efficiency of an integrated system, using processes of filtration for bivalves and absorption for macroseaweed, to improve the quality of the water of shrimp fisheries, was evaluated through the analysis of chemical, physical and biological variable. The effluent ones in question had been resultant of the mixture of heterotrophic culture of Litopenaeus vannamei, and Farfantepenaeus subtillis. . The native species Anomalocardia brasiliana (bivalve) and the macroseaweed Gracilaria sp. they had been selected had its potential it aquaculture to be found north-eastern of Brazil. This experiment was make in two phases of 48h with two treatments. In the first phase, the first treatment (control), only with aeration and as, added Anomalocardia brasiliana (5 ind//L) with aeration. Already for the second phase the control remained alone with aeration and in the other treatment the Anomalocardia brasiliana and substituted by the macroseaweed Gracilaria sp. was removed (1g/L). The experimental drawing for both phases contemplated six experimental units (tanks), belonging three to control and three to the treatment in the first phase with A. brasiliana and in the second phase with the macroseaweed Gracilaria sp. Water collect had been carried through in the initial schedule and after six in six hours. The concentrations of clorophyll-a, pheophytin, total phosphorus total phosphate, inorgânic phosphate total ammonium, nitrate, nitrite, alkalinity, temperature, dissolved oxygen, salinity turbidez and pH analyzed shown that the two organisms biological filters had significantly reduced the concentration of variables pollutants in the effluent. However it was observed that in the treatment it has controlled almost had a reduction to zero of nitrite concentration and a gradual increase of nitrate. And that, in the first phase in the treatment with shellfish, about 40% of A.brasiliana was removed deceased after the 48 hours of the experiment. Other studies must be facts, leading in account this reduction of the nitrite in the effluent one only with aeration in this space of time, and propitious a habitat more similar to the one of the nature to the A.brasiliana. / A eficiência de um sistema integrado, utilizando-se processos de filtração por bivalves e absorção por macroalgas, para melhorar a qualidade da água de viveiros de camarão, foi avaliada através da análise de variáveis químicas, físicas e biológicas . Os efluentes em questão foram resultantes da mistura de cultivos heterotróficos de Litopenaeus vannamei, e Farfantepenaeus subtillis. A Espécie nativa Anomalocardia brasiliana (bivalve) e a macroalga Gracilaria sp. foram selecionadas devido a seu potencial para a aqüicultura ser encontrado no Nordeste do Brasil. Este experimento se deu em duas fases de 48 h com dois tratamentos. Na primeira fase do experimento, o primeiro tratamento (controle), só com aeração e o segundo, adicionado Anomalocardia brasiliana (5 ind//L) com aeração. Já para a segunda fase o controle permaneceu só com aeração e no outro tratamento foi retirada a Anomalocardia brasiliana e substituída pela macroalga Gracilaria sp. (1g/L). O desenho experimental para ambas as fases contemplou seis unidades experimentais (tanques), pertencendo três ao controle e três ao tratamento na primeira fase com A. brasiliana e na segunda fase com a macroalga Gracilaria sp. Foram realizadas coletas de água no horário inicial e depois de seis em seis horas. As concentrações de clorofila-a, feofitina, fósforo total, fosfato total, fosfato inorgânico, amônia total, nitrato, nitrito, alcalinidade, temperatura, oxigênio dissolvido, salinidade turbidez e pH analisadas mostram que os dois organismos filtradores biológicos reduziram significativamente a concentração de variáveis poluentes no efluente. Entretanto foi observado que no tratamento controle houve uma redução a quase zero a concentração do nitrito e um aumento gradativo a nitrato. E que, na primeira fase no tratamento com marisco, cerca de 40% da A.brasiliana foi retirada morta após as 48 horas do experimento. Outros estudos devem ser feitos, levando em conta essa redução do nitrito no efluente só com aeração nesse espaço de tempo, e propiciar um habitat mais parecido com a da natureza à Anomalocardia brasiliana.
52

The role of terrestrial and phytoplankton-derived organic matter in planktonic food webs

Wenzel, Anja January 2012 (has links)
Lakes are important global ecosystems and many of them are nutrient-poor (unproductive). Especially in northern boreal latitudes, lakes may be heavily subsidized by terrestrial organic material (t-OM) from peat layers in the catchment. Thus, in addition to heterotrophic bacteria and phytoplankton, zooplankton may also use the particulate fraction of peat layer t-OM (t-POM) as a potential food source in those systems. Inputs of t-OM in northern latitudes are anticipated to increase in the future due to increasing precipitation and temperature. As t-OM is a good substrate for bacterial growth and as bacteria can often outcompete phytoplankton for inorganic nutrients, the proportions of heterotrophic bacteria and phytoplankton are expected to change in unproductive lakes. This may have pronounced impacts on zooplankton population dynamics. The aim of my thesis was to investigate how changes in food quality and quantity will affect metazoan zooplankton performance in unproductive lakes. Three laboratory studies assessed the quality of specific food components (phytoplankton, bacteria and peat layer t-POM) and their effects on Daphnia survival, growth and reproduction. Further, a mesocosm study with a full natural plankton community tested the predictions of the Light:Nutrient-Hypothesis in an unproductive clear water lake in situ by adding carbon and inorganic nutrients and changing light availability. I found that pure bacterial (Pseudomonas sp.) or t-POM diets could not sustain Daphnia populations, even though both were readily ingested. Daphnids needed at least 10-20% phytoplankton (Rhodomonas) in the diet to survive and even higher proportions (≥ 50%) were necessary for the production of viable offspring. Further, I showed that the dilution of non-limiting concentrations of Rhodomonas with increasing proportions of Pseudomonas or t-POM led to decreased Daphnia performance. Both Pseudomonas and t-POM lack essential biochemicals (fatty acids and sterols). In contrast, mineral nutrient limitation only occurred on t-POM-dominated diets as evidenced by a labeling experiment that showed Daphnia can incorporate carbon and phosphorus from Rhodomonas and Pseudomonas with similar efficiencies. Thus, peat layer t-POM was a lower quality food than Pseudomonas. This was corroborated by the finding that intermediate additions of Pseudomonas to limiting amounts of Rhodomonas supported increased Daphnia survival, growth and reproduction while t-POM additions had no beneficial effect. My results suggest that high terrestrial stable isotope signals in metazoan zooplankton are most likely derived from t-OM that is channeled tohigher trophic levels via the microbial loop (i.e. heterotrophic bacteria and/or bacterivorous protozoa) but not from direct metazoan feeding on t-POM. Furthermore, bacteria may serve as an important supplement to zooplankton diets when phytoplankton abundance is low. However, a sufficient proportion of high quality phytoplankton is always necessary to fulfil mineral and especially biochemical requirements of zooplankton in unproductive aquatic systems. The results of the mesocosm study showed that the Light:Nutrient-Hypothesis is not applicable to unproductive clear water systems in which the phytoplankton community is dominated by mixotrophs. In the face of the theoretical predictions, low light levels led to decreased zooplankton biomass. This was most likely caused by a shift in the algal community composition towards less edible taxa. Another reason may have been a weakening of the microbial loop. This is in line with the results of the laboratory studies that point out the importance of the microbial food web for zooplankton nutrition in unproductive lakes.
53

Benthic bacterial production in Eastern Townships and Laurentian lakes

Sander, Bettina Christa January 1993 (has links)
The $ sp3$H thymidine incorporation (TTI) method has been frequently used to estimate benthic bacterial production rates in well oxygenated marine and river sediments, but not in the frequently more reduced lake sediments. In chapter 1, I evaluate the published sediment production literature and examine useful predictors of in situ bacterial production in mostly marine and riverine sediments. In chapters 2 and 3, I estimated and compared benthic production rates by TTI, frequency of dividing cells (FDC), the dilution method (DIL) and sediment respiration (SR) in 13 Quebec lakes to assess the reliability of the TTI based production rates. The TTI method was first calibrated, but despite keeping incubation times short and at in situ temperature, using optimal sediment volumes to saturate $ sp3$H thymidine (TdR) uptake rates, and correcting production rates for $ sp3$H-DNA recovery efficiencies, only a maximum of 10% of $ sp3$H TdR was incorporated into DNA and only extracellular isotope dilution could be accounted for (chapter 2). Most problematic, however, is the increasing presence of active bacteria unable to take up and incorporate TdR as lake sediments become more reduced (chapter 3). TTI based results are also not nearly as well correlated to environmental factors as those obtained from SR. (Abstract shortened by UMI.)
54

Biogeochemistry of microbial biofilms in Devils Hole, Nevada

Madinger, Hilary L. 20 July 2013 (has links)
Little is known about the role of microbial biofilms in nutrient cycling and ecosystem processes within desert springs. Furthermore, the difference between nutrient limitation of biofilms in desert springs and other ecosystems is unknown. Biofilms produce micro-scale physicochemical variation important to ecosystem function. We measured the variation in microscale physicochemical heterogeneity in biofilms of Devils Hole, Nevada. Microelectrodes were used to measure micro-scale chemical gradients of temperature, pH, O2, and H2S in addition to water column and pore water nutrient measurements in Spirogyra, cyanobacteria, and Beggiatoa biofilms over one year. Biofilm physicochemical gradients were used to calculate diffusion and metabolic rates. The rate of O2 and H2S diffusion ranged over two orders of magnitude. Biofilm production and respiration were influenced by biofilm type, light exposure, and sample month. Maximum O2 production occurred in spring and summer during direct light exposure. Oxygen production and consumption varied with light exposure and season. The H2S production and consumption varied with biofilm type. Higher concentrations of SO4 in Beggiatoa suggested that H2S production in Beggiatoa was quickly oxidized in the ecosystem. Spirogyra and cyanobacteria followed similar physicochemical trends; however, Spirogyra had more pronounced diurnal and seasonal variation. The differences between cyanobacteria and Spirogyra have implications on the ecosystem function of Devils Hole as well as other ecosystems with diverse biofilm communities. The heterogeneous physicochemistry of microbial biofilms and the differences in biofilm nutrient limitation suggests that a change in microbial biofilms or nutrient concentrations could alter ecosystem biogeochemical dynamics. Additionally, we assessed the nutrient limitation of two desert springs in comparison with a temperate stream. A nutrient diffusing substrata experiment was used to measure chlorophyll a, respiration, and biomass with phosphorus, nitrogen, and sulfide treatments. Autotrophic and heterotrophic biofilms responded differently to treatments and the temperate stream had higher chlorophyll a biofilm accrual but lower respiration relative to the desert springs. / Spatial and temporal variation of microbial biofilm biogeochemistry in a desert spring, Devils Hole, Nevada -- Autotrophic and heterotrophic nutrient limitation across biomes. / Department of Biology
55

Les Particules d'Exopolymères Transparentes (Transparent Exopolymer Particles, TEP) en milieu pélagique lacustre : relation avec le phytoplancton et rôle dans les réseaux trophiques microbiens / Transparent Exopolymer Particles (TEP) in lake pelagic environment : relationship with phytoplankton and role in microbial food webs

Arnous, Mohamad Bashir 16 November 2010 (has links)
Ce travail est une contribution à la connaissance de l’importance des particules de nature polysaccharidique, les TEP (Transparent Exopolymer Particles) ou particules d’Exopolymères Transparentes, en milieu pélagique lacustre.Les différentes études présentées dans ce mémoire se sont essentiellement focalisées sur la distribution de ces particules et leur relation avec le phytoplancton et les autres microorganismes du réseau trophique aquatique en milieu naturel (le lac Pavin, oligo-mésotrophe et le réservoir hypereutrophe de Grangent) et en conditions semi contrôlées(enclos limniques installés sur le lac de Créteil). Les résultats de l’étude printanière au lac Pavin indiquent que la majorité des TEP sont colonisées par les bactéries et que l’intensité de colonisation est fortement liée à la température et diminue avec l’augmentation en taille des particules. La distribution des nanoflagellés hétérotrophes (HNF) est fortement liée à la densité des TEP mais pas à l’intensité de colonisation de ces particules. L’abondance et la surface cumulée de TEP sont significativement plus élevées dans le lac oligo-mésotrophe que dans le réservoir hypereutrophe de Grangent. Les abondances et les concentrations élevées de particules dans le lac Pavin coïncident avec la présence de diatomées de grande taille au printemps et en automne et avec les chlorophycées à la fin de l’été.Dans le réservoir de Grangent les valeurs maximales de TEP coïncident avec le développement de la cyanobactérie Microcystis aeruginosa. Si les TEP augmentent avec la productivité de l’écosystème, la production de ces particules par unité de chlorophylle a dépend de la composition algale et tend à diminuer avec l’augmentation du niveau trophique du milieu. Les résultats issus de la biomanipulation en enclos limniques indiquent que la structure du réseau trophique aquatique (par la présence ou l’absence de poissons planctonophages) influence fortement la distribution,la dynamique et le spectre de taille des TEP. Dans le traitement poisson, l’abondance des TEP, la chlorophylle a et la biomasse des chlorophycées sont fortement corrélées. De par son broutage sur le phytoplancton, le zooplancton a un effet négatif sur les TEP dans le traitement sans poissons mais il contribue sans doute à la formation de TEP e tinfluence le spectre de taille de ces dernières dans ce traitement. Ce travail souligne l’importance des particules de nature polysaccharidique en milieu pélagique lacustre qui doivent être considérées comme une part importante du carbone organique qui transite des producteurs primaires vers les décomposeurs et vers le sédiment. / This work adds to the knowledge of the significance of polysaccharidic detrital particles or TEP (= Transparent Exopolymer Particles) in freshwater pelagic environments. Studies in this thesis have mainly focused on the distribution of TEP and their relationships with phytoplankton and other microorganisms in natural environments (the oligo-mesotrophic Lake Pavin and the hypereutrophic reservoir of Grangent) and in limnetic enclosures (lake of Créteil). The intensity of bacterial colonization during spring in Lake Pavin was strongly related to temperature and decreased with particle size. The abundance of heterotrophic nanoflagellates (HNF) in this lake was more significantly related to the density of the particles than to the density of total bacteria and the intensity of bacterial colonization of TEP, suggesting that TEP is a more important factor for HNF development than attached and free bacteria. The abundance and the total surface area of the particles were significantly higher in the hypereutrophic Lake Grangent than in the mesotrophic Lake Pavin. Maximum TEP density in Lake Pavin was recorded during the spring diatom bloom, while TEP concentration peaked in late summer when the phytoplankton community was largely dominated by small-size chlorophytes with an abundant polysaccharide cell coating. In the hypereutrophic Lake Grangent,maximum values of TEP appeared during the summer development of the cyanobacterium Microcystis aeruginosa. Per cell production of TEP, expressed by the ratio between TEP concentration and chlorophyll a concentration, was significantly higher in the less productive lake and the analysis of the size spectra of the particles indicated a greater proportion of small particles in this lake. TEP therefore appear as more significant for microbial development and aggregates formation in the less productive environment. Results from limnetic enclosures (either dominated by planktivorous fish or fishless) indicated that food-web structure strongly influences the distribution and size spectra of TEP. TEP abundances were related to chlorophyll a concentrations and the biomass of chlorophytes in the fish treatment. As expected by the trophic cascades theory, zooplankton had an indirect negative effect on TEP abundance. Our results suggest, however, that metazoan probably influence the formation and the size spectra of the particles in the fishless treatment. TEP must be regarded as a major part of the organic carbon which is transferred from the primary producers to the microbial food web and the sediments in freshwater ecosystems.
56

MODELAGEM TÉCNICO-ECONÔMICA DA APLICAÇÃO DE BIORREATORES HETEROTRÓFICOS MICROALGAIS NO TRATAMENTO DE EFLUENTES AGROINDUSTRIAIS / TECHNO-ECONOMIC MODELING OF THE MICROLGAE HETEROTROPHIC BIOREACTORS APPLICATION IN AGROINDUSTRIAL WASTEWATER TREATMENT

Roso, Gabriela Rigo 10 March 2015 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The project aimed to carry out the techno-economic modeling of the heterotrophic microalgae bioreactors application in the poultry and swine abattoirs and processing wastewater treatment and possible exploitation of bioproducts from biomass generated in the process. The project focus was directed to the techno-economic modeling of bioprocesses following: (i) agroindustrial wastewater treatment and integral biomass production (ii) obtaining of bulk oil and lipid extracted algal (LEA) as feedstock for biodiesel conversion process and protein production (iii) obtaining of microalgal carotenoid-rich oleoresin solubilized in soybean oil. The results indicated that the agroindustrial wastewater treatment costs and production of microalgal biomass were USD 2.66 per cubic meter and USD 30 per ton of dried biomass respectively. The obtaining of bulk oil and LEA had a production cost of approx. USD 386.5 and 70.4 per ton. Finally, the oleoresin produced had an estimated production cost in USD 146.9 per kilogram. The results evidenced that the techno-economic modeling of the heterotrophic microalgae bioreactors application are an alternative to substantially minimize the production costs, giving economic sustainability to the agroindustry of poultry and swine processing. / O projeto teve por objetivo realizar a modelagem técnico-econômica da aplicação de biorreatores heterotróficos microalgais no tratamento de efluentes provenientes do abate e processamento de aves e suínos e possível exploração dos bioprodutos provenientes da biomassa gerada no processo. O foco do projeto foi direcionado à modelagem técnicoeconômica dos seguintes bioprocessos: (i) tratamento do efluente agroindustrial e produção de biomassa integral (ii) obtenção de óleo a granel e farelo microalgal desengordurado, como matéria-prima para o processo de conversão de biodiesel microalgal e produção de proteína (iii) obtenção de oleorresina de carotenóides mistos solubilizada em óleo de soja a partir de microalgas. Os resultados indicaram que os custos de tratamento do efluente agroindustrial e produção de biomassa microalgal foram US$ 2,66 por m³ de efluente e US$ 30 por tonelada de biomassa seca respectivamente. A obtenção de óleo a granel e farelo de microalgas obtiveram um custo de produção de US$ 386,5 e 70,4 por tonelada de óleo e farelo, respectivamente. Por fim, a oleorresina produzida teve um custo de produção estimado em US$ 146,9 por quilograma. Os resultados evidenciaram que a modelagem técnico-econômica da aplicação do biorreator heterotrófico microalgal, são uma alternativa para minimizar substancialmente os custos de produção, dando sustentabilidade econômica às agroindústrias de processamento de aves e suínos.
57

AvaliaÃÃo do comportamento bacteriano e alteraÃÃes sensoriais em tilÃpias do Nilo (Oreochromis niloticus) durante estocagem em gelo / PERFORMANCE EVALUATION AND BACTERIAL CHANGES IN SENSORY NILE TILAPIA (Oreochromis niloticus) DURING STORAGE IN ICE

Lana Oliveira Leite 27 February 2013 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O pescado à um alimento susceptÃvel à deterioraÃÃo devido Ãs suas caracterÃsticas intrÃnsecas, sendo necessÃrio o monitoramento bacteriano no armazenamento pÃs-morte. Dessa forma, objetivou-se quantificar bactÃrias, psicrotrÃficas, psicrÃfilas e mesÃfilas em tilÃpias do Nilo (Oreochromis niloticus) durante 21 dias de estocagem sob aÃÃo do gelo. Foram realizados quatro experimentos, separados em dois grupos, nÃo eviscerados e eviscerados, cada um com oito amostras perfazendo um total de 32 amostras. A cada trÃs dias era retirado um exemplar de tilÃpia para as anÃlises do experimento: sensorialmente, conforme a avaliaÃÃo do MÃtodo do Ãndice de Qualidade (MIQ), adaptado à tilÃpia do Nilo e microbiologicamente. Na anÃlise sensorial do peixe cru foram avaliados os atributos: aspecto geral, olhos, brÃnquias, textura e musculatura dos peixes, segundo os somatÃrios dos caracteres sensoriais (S.C.S). De cada exemplar foram quantificados os grupos bacterianos: psicrotrÃficos (7ÂC), psicrÃfilos (23ÂC), e mesÃfilos (35ÂC), na superfÃcie e no mÃsculo, pelo mÃtodo de Contagem PadrÃo em Placas (CPP). NÃo houve diferenÃa estatÃstica entre os trÃs grupos bacterianos analisados à um nÃvel de significÃncia de 5% dentro dos mesmos tratamentos e entre os grupos. O tempo de estocagem apresentou alta correlaÃÃo com a contagem dos grupos bacterianos e o aumento do MIQ, tanto para os peixes eviscerados, quanto para os nÃo eviscerados. Foi considerado que o processo de evisceraÃÃo no local de venda dos peixes nÃo aumentou sua vida Ãtil. Sugere-se, portanto, uma maior atenÃÃo no processo de evisceraÃÃo em peixarias que comercializam peixes vivos, pois esse processo nÃo foi realizado de forma eficaz para seguranÃa e valorizaÃÃo do produto. / Fish is a food susceptible to deterioration due their intrinsic characteristics, requiring bacterial monitoring in postmortem storage. Thus, the objective was to quantify mesophilic, psychrotrophic, psychrophilic bacteria in Nile tilapia (Oreochromis niloticus) during to 21 days of storage under the action of ice at temperature refrigeration. Four experiments were conducted, separated to two groups, gutted and ungutted, with eight samples totaling 32 samples. Every three days was taken a exemplar of tilapia for analyzes of the trial: sensory evaluation according to the Quality Index Method (QIM) adapted to the Nile tilapia and heterotrophic bacterial count of cultivable. In sensory analysis of raw fish attributes were assessed: general appearance, eyes, gills, muscles and texture of the fish, according to the Sensory Characters Sum (S.C.S). To each specimen were quantified bacterial groups: psychrophilic (23 ÂC), psychrotrophic (7 ÂC) and mesophilic (35 ÂC), the surface and the muscle, using the method of standard plate count (SPC). There was no statistical difference between the three bacterial groups analyzed the significance level of 5% within the same treatments and between groups. The storage time was highly correlated with the counting of bacterial groups and increased QIM for both eviscerated fish, and for those not drawn. It was considered that the process of evisceration on the premises of the fish did not increase its useful life. It is suggested, therefore, greater attention in the process of gutting fish markets that sell live fish, because this process was not carried out effectively to security and recovery product.
58

Isolamento e Caracterização de Cepas Shewanella Sp. Do Cultivo Heterotrófico de Litopenaeus Vannamei (Boone, 1931)

SANTOS, Rogério William 20 February 2014 (has links)
Submitted by Haroudo Xavier Filho (haroudo.xavierfo@ufpe.br) on 2016-03-04T16:25:51Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Roger Dissertação Mestrado 2014_ versão Final biblioteca_ Entregue_.pdf: 1359994 bytes, checksum: ce3bbcf3906e6cb72bdfea9a7b7e7d06 (MD5) / Made available in DSpace on 2016-03-04T16:25:51Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Roger Dissertação Mestrado 2014_ versão Final biblioteca_ Entregue_.pdf: 1359994 bytes, checksum: ce3bbcf3906e6cb72bdfea9a7b7e7d06 (MD5) Previous issue date: 2014-02-20 / CAPES / CNPq / FINEP / O gênero Shewanella é um representante da classe das Gammaproteobactérias, família Shewanellaceae, compondo um grupo de bactérias gram-negativas, móveis, baciliforme, oxidase positiva, comumente encontrada em ambiente marinho e isolada do trato digestivo de animais aquáticos. Devido a suas características vem sendo amplamente testado como probiótico na carcinicultura. Estes têm sido utilizados na aquicultura para o controle biológico, aumento da taxa de conversão alimentar e sistema imune dos camarões. Este estudo teve por objetivo identificar potenciais bactérias probióticas retiradas do hepatopâncreas e estômago do camarão cultivado em sistema heterotrófico, avaliar as relações filogenéticas das cepas com o gênero Shewanella e caracteriza-las através de análisesmorfológicas, bioquímicas, produção de biofilme e antibiograma. A partir do cultivo heterotrófico de Litopenaeus vannamei, foram selecionadas as cepasIPA-S.51, IPA-S.111 e IPA-S.252para identificação através do sequenciamento parcial do gene 16S rRNA e comparados ao GenBank – NCBI e RDP - Seqmatch. As cepas foram alinhadas a 45 espécies do gênero Shewanella e avaliadas filogeneticamente utilizando os métodos Neighbor-Joining, Máxima Verossimilhança e Inferência Bayesiana. Quanto àsanálises morfológicas foram avaliadas parâmetros de acordo com a similaridade a padrões estabelecidos. Os testes bioquímicos foram realizados com o auxílio dos kits BACTRAY I, BACTRAY II e BACTRAY III (Labroclin®), totalizando 30 testes bioquímicos. A avaliação da capacidade de formação de biofilme foi realizada segundo Christensen e colaboradores. No antibiograma as cepas bacterianas foram submetidas a 13 antibióticos distintos segundo à técnica de Kirby e Bauer, com três repetições. O sequenciamento das cepas revelou alta similaridade a espécie Shewanella algae, utilizando o GenBank e o RDP-seqmath. A Inferência Bayesiana apresentou maior aporte estatístico e fidelidade dentre os métodos analisados. A Shewanella upenei apresentou alta similaridade as cepas estudadas, assim como a S. algae. As análises filogenéticas não descartam a hipótese de novas espécies para IPA-S.51, IPA-S.111 e IPAS. 252. As cepas estudadas foram sensíveis aos antibióticos Ampicilina/Subactan, Ofloxacina e Tetraciclina. A caracterização fenotípica fortalece a hipótese de especiação para as cepas testadas. Portanto, a capacidade de formação de biofilme, adicionada ao alto potencial enzimático e antagonismo a patógenos, característico do gênero Shewanella, tornam estas cepas potenciais probióticos para carcinicultura. / The genus Shewanella is one representant of Gammoproteobacteria class, family Shewanellaceae, being part of gram-negative bacteria group, mobile, bacilliform, oxidasepositive, commonly found on marine environments and isolated from the digestive tract of aquatic animals. Due to its characteristics, some tests as probiotics are being carried out in carciniculture. They are being used on aquaculture for biological control, augmentations on feed conversion rates and immune system of shrimps. This study has as objective identify potentials probiotics bacteria found in the hepatopancreas and stomach of shrimps cultivated on heterotrophic based system, evaluating the strain phylogenetic relationships with Shewanella genus and characterizing them through morphological and biochemical analysis, biofilm production and antibiogram. The strains IPA-S.51, IPA-S.111 e IPA-S.252 were selected from the heterotrophic cultivation of Litopenaeus vannamei, identified through partial 16S rRNA sequencing and compared to GenBank – NCBI and RDP - Seqmatch.The strains were aligned to 45 species of Shewanella genus and phylogenetically evaluated using Neighbor-Joining,Maximum-Likelihood estimation and Bayesian Inference.Regarding the morphological analysis parameters were evaluated according with established standard similarities. The biochemical tests were conducted with the assistance of BACTRAY I, BACTRAY II and BACTRAY III (Labroclin®) kits, totalizing 30 biochemical tests.The Biofilm capacity evaluation was made according Christensen et al. Regarding the antibiogram, the bacterial strains had undergone 13 distinct antibiotics according Kirby and Bauer, with three repetitions. The strains sequencing showed high similarity to Shewanella algae species, using GenBank and RDP-seqmath.The Bayesian inference displayed higher statistic contribution e fidelity among the other methods.The Shewanella upenei showed high similarity to the strains in study also as Shewanella algae.The phylogenetic analysis does not exclude the hypothesis of IPA-S.51, IPA-S.111 e IPA-S.252 being new species.The strains studied were sensitives to the antibiotics Ampicillin/Sulbactam, Ofloxacin, Tetracyclin. The phenotypic characterization of the strains supports the hypothesis of speciation. Thus, the capacity of biofilm formation plus the high enzymatic potential and antagonism interactions to pathogens, characteristics found in the Shewanella genus, make these strains potential probiotics to carciniculture.
59

Isolamento e identificação de bactérias de cultivo heterotrófico de Litopenaeus vannamei

GOUVEIA, Carolina Kropniczki 31 January 2012 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-03-16T15:01:11Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) CAROLINA KROPNICZKI GOUVEIA - DISSERTAÇÃO.pdf: 1168935 bytes, checksum: ec9fc0cb4665cb4641bd7162f5449c56 (MD5) / Made available in DSpace on 2016-03-16T15:01:11Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) CAROLINA KROPNICZKI GOUVEIA - DISSERTAÇÃO.pdf: 1168935 bytes, checksum: ec9fc0cb4665cb4641bd7162f5449c56 (MD5) Previous issue date: 2012 / A produção de camarões marinhos na região Nordeste do Brasil vem crescendo principalmente pela introdução da espécie Litopenaeus vannamei. Adicionadas à dieta ou diretamente na água, as bactérias probióticas têm sido utilizadas para controle biológico e aumento da digestibilidade alimentar e do sistema imune dos animais, elevando a lucratividade dos empreendimentos dedicados à carcinicultura. A influência de enzimas exógenas de bactérias na digestão dos camarões não está bem elucidada e ainda existe uma grande lacuna no que diz respeito a aspectos nutricionais tanto dos microrganismos, quanto dos animais cultivados. Dessa forma, objetivou-se avaliar as atividades proteolítica e amilolítica de cepas bacterianas isoladas do hepatopâncreas e estômago do L. vannamei e identificar as bactérias produtoras destas enzimas pelo sequenciamento do gene 16S rRNA. Para estudo do ambiente em tanques heterotróficos experimentais utilizando dois probióticos comerciais (HP1 e HP2) e em tanques controles heterotrófico (Het) e autotrófico (Aut), amostras de água foram tomadas ao final do experimento para contagem de bactérias heterotróficas, autotróficas e víbrios por plaqueamento em meios específicos. As médias de população bacteriana foram submetidas à análise de variância (ANOVA) complementada pelo teste de Tukey (p<0,05). Dos órgãos das amostras de camarão (n=3) foram retirados os materiais internos para isolamento das cepas bacterianas e seleção in vitro pela capacidade de produção de enzimas digestivas. Uma cepa de Bacillus subtilis (ATCC 6633) foi utilizada como testemunha na identificação utilizando os inicializadores universais para o domínio bactéria fD1 (Forward) e rD1 (Reverse). A população de bactérias heterotróficas foi mais representativa quando comparada às de autotróficas e víbrios, e o experimento Het atingiu a maior média (1,91x107 UFC/mL). As menores cargas de víbrios foram encontradas nos tanques experimentais HP1 e HP2 com médias de 2,46x104 e 2,00x104 UFC/mL, respectivamente. De 64 cepas isoladas, 11 possuíram índices enzimáticos satisfatórios (IE ≥ 2,0) para a produção de protease e amilase. Os amplicons após sequenciamento do DNA apresentaram tamanho maior que 1,4Kb e homologia com o GenBank e RDP, identificando bactérias como Bacillus subtilis e Shewanella algae. O incremento da população heterotrófica está relacionado à adição de melaço como fonte de carbono no sistema de cultivo e nos experimentos com os probióticos comerciais, a carga vibrionácea foi reduzida. A técnica de sequenciamento do gene 16S rRNA utilizando os primers fD1 e rD1 foi eficiente na caracterização bacteriana a nível de espécie e até subespécie, revelando a presença de bactérias com potencial para utilização como probiótico. / The marine shrimps cash crop in the Northeast region of Brazil is raising due to the introduction of Litopenaus vannamei. The probiotics bacteria added in the diet or directly in the water have been used for biological control and augmentations in the alimental digestibility and in the immune system, increasing the profits of enterprises related to carciniculture. The influence of bacterial exogenic enzymes on shrimp digestion is not clear and still has a gap concerning the nutrition aspects of shrimps and microorganisms. Therefore, this study had as objective the evaluations of proteolytic and amylolytic activities of bacterial strains isolated from hepatopancreas and stomach of L. vannamei and identify the bacteria responsible for enzymes production by sequencing the 16S rRNA gene. For environmental study in heterotrophic tanks using two commercial probiotics (HP1 e HP2) and in heterotrophic (Het) and autotrophic (Aut) control tanks, water samples were collected at the end of the experiment in order to count the autotrophic and heterotrophic bacteria and vibrio by plating in specific media. The means of bacterial population were submitted to variance analysis (ANOVA) and complemented by Tukey’s test (p<0.05). Internal materials were extracted from shrimp organs samples (n=3) in order to isolate the bacterial strains and “in vitro” selection due to its capacity to produce digestive enzymes. One strain of Bacillus subtilis (ATCC 6633) was used as witness on the identification using the universal primers fD1 (Forward) e rD1 (Reverse). The population of heterotrophic bacteria was more representative compared with autotrophic and vibrio population and the Het experiment presented the greatest mean (1,91x107 CFU.mL-1). The minor loads of vibrio were found in the experimental tanks HP1 and HP2 with means 2,46x104 e 2,00x104 CFU.mL-1 respectively. From sixty four strains, only eleven showed satisfactory enzymatic index (EI ≥ 2.0) to protease and amylase production. The amplicons after the DNA sequencing showed sizes bigger than 1,4Kb and homology with GenBank e RDP, identifying bacteria as Bacillus subtilis and Shewanella algae. The increment of heterotrophic population is related with the addition of molasses as carbon source in the crop system and the vibrio load were reduced in the experiments with commercial probiotics. The sequencing technique of 16S rRNA gene using fD1 and rD1 were efficient in the characterization of bacteria at the level of species and even at the level of subspecies, revealing the presence of bacteria with potential use as probiotic.
60

Modifications métaboliques et structurelles des communautés de bactéries marines exposées à différentes qualités de matière organique / Metabolic and composition changes in marine bacterial community esposed to variable natural organic matter bioreactivity

Blanchet, Marine 16 January 2015 (has links)
En milieu marin, les communautés bactériennes hétérotrophes sont exposées à un mélange hétérogène de composés organiques dissous présentant différents degrés de labilité, qui peuvent contrôler à la fois leurs activités et leur composition. Dans le cadre de cette thèse, nous avons étudié la réponse de communautés bactériennes présentes dans des environnements côtiers contrastés à l’ajout simple ou combiné de différentes sources naturelles de matière organique dissoute (MOD), préalablement photo oxydée ou non et présentant différentes bio réactivités. Dans un premier temps, nous avons étudié l’impact d’ajout de MOD labile provenant de méduses sur l’activité et la diversité bactériennes d’une communauté d’une lagune côtière méditerranéenne. Nous avons observé que la résilience des communautés bactériennes suite à cet ajout était plus importante pour les fonctions métaboliques que pour la diversité. Ceci suggère que les efflorescences de méduses peuvent entrainer des changements durables de la structure des communautés bactériennes en environnement côtier. Dans un deuxième temps, nous nous sommes intéressés à la possibilité d’un priming effect (accélération de la dégradation bactérienne de la MOD réfractaire en présence de MOD labile) en milieu côtier. Des expériences d’ajout simple ou combiné de MOD labile et récalcitrante ont été réalisées sur des communautés bactériennes de Mer Méditerranée et d’un fjord de Patagonie chilienne. Dans les deux cas, nous avons observé des changements plus importants de la composition communautaire bactérienne suite à un ajout combiné. Cependant, nous n’avons pas observé une plus forte consommation de MOD récalcitrante suite à l’ajout de composés labiles, ce qui suggère que le priming effect n’a pas eu lieu au cours de nos expériences. Enfin, nous avons étudié l’impact de la photodégradation de différentes sources de MOD (i.e. MOD récalcitrante de rivière, MOD labile provenant de phytoplancton) sur l’activité et la diversité de communautés bactériennes côtières. Nous avons observé que la photodégradation de la MOD issue d’une culture de phytoplancton entrainait à la fois une croissance bactérienne plus faible et une modification de la diversité bactérienne en faveur des Alphaprotéobactéries. / Heterotrophic bacterial communities in marine environment are exposed to a heterogeneous mixture of dissolved organic compounds with different bioavailability that may control both their activities and their composition. In the frame of this thesis, we studied the response of different coastal bacterial communities to the single or combined addition of various natural dissolved organic matter (DOM) photo-oxidized or not, presenting different bioavailability characteristics. Firstly, we studied the effects of the addition of highly bioreactive DOM derived from jellyfish on bacterial activities and community structure in a Mediterranean coastal lagoon. We observed that resilience of the bacterial community after the addition of DOM from the jellyfish was higher for metabolic functions than diversity, suggesting that jellyfish blooms can induce durable changes in the bacterial community structure in coastal lagoons. Secondly, we investigated the occurrence of priming effect (increase in microbial degradation of refractory DOM upon the addition of labile DOM) on coastal marine environments. Experiments with single or combined additions of recalcitrant and labile DOM sources were performed with a Mediterranean and a Patagonian fjord bacterial communities. In both cases we observed a greater effect of combined addition on bacterial community composition. However we did not observe an increase in recalcitrant DOM degradation of recalcitrant DOM following the addition of labile compounds, suggesting that priming effect did not occur during our experiments. Finally, we studied the impact of contrasted DOM (i.e. recalcitrant riverine DOM, labile phytoplankton-derived DOM) photodegradation on coastal bacterial communities activity and composition. We observed that photodegradation of phytoplankton-derived DOM led to a lower bacterial growth and changes in bacterial community diversity, in favour of Alphaproteobacteria.

Page generated in 0.0507 seconds