Дисертації з теми "Host-microbiome interaction"
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Tamarelle, Jeanne. "Composition et dynamique du microbiote vaginal : facteurs associés et rôle dans l’infection par Chlamydia trachomatis The vaginal microbiota and its association with human papillomavirus, Chlamydia trachomatis, Neisseria gonorrhoeae and Mycoplasma genitalium infections: a systematic review and meta-analysis Vaginal microbiota composition and association with prevalent Chlamydia trachomatis infection: a cross- sectional study of young women attending a STI clinic in France Nonoptimal Vaginal Microbiota After Azithromycin Treatment for Chlamydia trachomatis Infection." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLV097.
Повний текст джерелаChlamydia trachomatis (CT) is a sexually transmitted bacteria responsible for cervicitis, urethritis, and pelvic inflammatory diseases leading to subsequent tubal infertility and ectopic pregnancies. It is the most frequent sexually transmitted infection worldwide, including in France. Epidemiological data indicate that the incidence rate is increasing despite the implementation of control measures, which motivates the revision of current screening strategies. The vaginal microbiota could play a major role in preventing sexually transmitted infections through ecological competition and metabolites, such as lactic acid production. The vaginal microbiota corresponds to a fine-tuned equilibrium likely to be modified by exposures such as sexual practices, hygiene practices, antibiotics but also presence of pathogens. The overall objective of this thesis is to study the association in this triangle composed of external exposures, vaginal microbiota and CT infection, through the study of the vaginal microbiota composition and dynamics. We aimed at answering these questions: are there biomarkers of CT infection in the vaginal microbiota? Are the vaginal microbiota composition and structure modified by CT infection and antibiotic consumption? What are the exposures associated with perturbations of the vaginal microbiota? To answer these questions, the first step consisted of a state of the art to estimate the association between vaginal microbiota and CT infection in the literature, as well as three other clinically relevant sexually transmitted infections, and to evaluate the role of several factors in the observed heterogeneity between studies. In a second step, we estimated this association using molecular characterization of the vaginal microbiota in two studies in France and in the United States. We showed that Lactobacillus iners-dominated communities (CST III) and Lactobacillus-deprived communities (CST IV) were over-represented among CT-positive women. By studying the vaginal microbiota after azithromycin treatment and CT clearance in the American study, we showed that the vaginal microbiota did not evolve towards an optimal state, suggesting that women may stay at risk of CT reinfections. Finally, in two longitudinal studies using frequent sampling in the United States, we studied exposures associated with incidence and clearance of a CST IV. We showed that when the vaginal microbiota was not dominated by L. iners, menses was the main factor associated with incidence and clearance of a CST IV, while for women whose vaginal microbiota is dominated by L. iners, menses but also lubricant use, douching, ethnic origins, age and condomless vaginal sex were associated with CST IV incidence and/or clearance. Therefore, this thesis allowed on the one hand to confirm the association between Lactobacillus-deprived vaginal microbiota and CT infection using genome sequencing, and on the other hand to single out L. iners from other Lactobacillus spp. and to evaluated the risk associated with CST III. By enabling a better understanding of the natural history of CT and of the vaginal microbiota dynamics, we hope to contribute to improving strategies for the control of CT infection and other STIs. The innovative potential of the project lies in the use of molecular methods, which allows refining of our approach of health management by integrating individual predisposition to sexually transmitted infections, thus paving the way for personalized medicine
Sieksmeyer, Thorben [Verfasser]. "Host-microbiome-pathogen interactions in cockroaches / Thorben Sieksmeyer." Berlin : Freie Universität Berlin, 2021. http://d-nb.info/1231276096/34.
Повний текст джерелаJacob, Staffan. "Microbiome, communication and reproduction : host-microbiome interactions and parent-offspring communication in birds." Toulouse 3, 2013. http://www.theses.fr/2013TOU30166.
Повний текст джерелаHost-microbiome interactions have been pointed out to be potentially responsible for the evolution of numerous life history traits throughout the animal kingdom. However, experimental approaches are still lacking to support this hypothesis. In this thesis, we experimentally investigated the effects of the microbiome on the costs of reproduction, nestling development, communication and antimicrobial defences in Great tits (Parus major). Firstly, we showed that the microbiome mediated host oxidative damages inherent to investment in reproduction. Secondly, we found that females adjusted their investment of carotenoids in eggs depending on their microbiome, and that microbial exposure affected nestling growth and condition at fledging. Thirdly, our results suggest that microorganisms did not degrade feather colouration in wild birds, but microbial exposure during reproduction affected investment in new feathers during the following moult. Finally, we found that birds modified their investment in the uropygial gland, an external organ involved in the regulation of feather microbial communities, according to their microbiome. This antimicrobial strategy that differs between sexes could thus allowed regulation of feather microbiome. Our results consequently provide the first experimental evidence for the hypothesis that the microbiome plays a role in the evolution of host life history traits
Alvarez, Contreras Carlos Alberto. "HOST-MICROBIOME INTERACTIONS AND REGULATION OF THE IMMUNE SYSTEM." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1600446008947681.
Повний текст джерелаMestdagh, Renaud. "Role of gut microbiome-host metabolic interactions in metabolic diseases." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/10003.
Повний текст джерелаIbrahim, Khalid Subhi. "Biochemical interactions between the gut microbiome and host in obesity/type II diabetes." Thesis, Glasgow Caledonian University, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.743906.
Повний текст джерелаBoulange, Claire. "Metabonomic investigations of the mammalian host-gut microbiome interactions in obesity and metabolic diseases." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/24727.
Повний текст джерелаDesai, Prerak T. "Molecular Interactions of Salmonella with the Host Epithelium in Presence of Commensals." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1059.
Повний текст джерелаYoo, Christopher Charles. "Investigating the Role of Trimeric Autotransporter Adhesins in Fusobacterium nucleatum Pathogenesis." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/101683.
Повний текст джерелаMaster of Science in Life Sciences
Harrison, Christy Anne, and Christy Anne Harrison. "The Role of Dysfunctional Na+/H+ Exchange in the Development of Dysbiosis and Subsequent Colitis." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625602.
Повний текст джерелаLassudrie, Malwenn. "Effets combinés des dinoflagellés toxiques du genre Alexandrium et d'agents pathogènes sur la physiologie des bivalves." Thesis, Brest, 2014. http://www.theses.fr/2014BRES0113/document.
Повний текст джерелаBivalve populations undergo regular epidemics that weaken or decimate exploited stocks and thus limit aquaculture. These diseases are caused mainly by viruses, bacteria or parasites, and occur primarily during spring and summer. This period of the year also provides favorable conditions for toxic dinoflagellate blooms, including species of the genus Alexandrium. Thus, the risk of Alexandrium sp. blooms and infectious diseases co-occurring in bivalves is high. However, these micro-algae synthesize and excrete toxins and cytotoxic compounds responsible for physiological changes in bivalves and could lead to an immuno-compromised status.The objective of this thesis is to evaluate the combined effects on bivalve physiology of exposure to the toxic dinoflagellate, Alexandrium sp., and infection by pathogens, through the study of different bivalve - pathogen - Alexandrium sp. tripartite interactions. The results of this work highlight the species-specific nature of these impacts.Thus, exposure to Alexandrium catenella reduces the herpesviruses infection in oyster Crassostrea gigas, whereas the dinoflagellate A. fundyense increases the susceptibility of C. virginica oyster to the parasite Perkinsus marinus, probably via immuno-suppression, as suggested by the partial inhibition of hemocyte responses. Additionally, the effect of a toxic algal bloom on oyster susceptibility to opportunistic diseases when exposed to a new microbial environment (simulating a transfer) was evaluated. Hemocyte responses to a changing microbial environment were suppressed by exposure to A. catenella, although no new bacterial infection was detected.Finally, exposure to pathogens or to a new microbial environment interferes with the processes by which oysters exposed to A. catenella accumulate algal toxins, illustrating the complexity of these interactions. These results provide a better understanding of the involvement of toxic algal blooms in the development of diseases affecting commercial bivalve species, but also of the involvement of the bivalve biotic environment in the accumulation of regulated toxins
Daniel, Scott G., Corbie L. Ball, David G. Besselsen, Tom Doetschman та Bonnie L. Hurwitz. "Functional Changes in the Gut Microbiome Contribute to Transforming Growth Factor β-Deficient Colon Cancer". AMER SOC MICROBIOLOGY, 2017. http://hdl.handle.net/10150/626089.
Повний текст джерелаBaudry, Lyam. "Investigating chromosome dynamics through Hi-C assembly." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS026.
Повний текст джерелаThe advent of high-throughput DNA sequencing technologies has set off an expanding trend in genome assembling and scaffolding. Such genome quality is an essential preliminary to understand interactions between and among chromosomes. We built upon a computational and technological framework that let us tackle genome assembly problems of increasing complexity. Our methods are mainly based on chromosome conformation capture technologies such as Hi-C. In a Hi-C experiment, DNA molecules are cross-linked with the surrounding proteins and form a large, static protein-DNA complex. This captures the spatial conformation by trapping together molecules that are physically close to each other. Therefore, Hi-C is very suitable for 3D genome structure analysis, which lets us infer a wealth of information about the genome. It was indeed shown that the tridimensional structure of the genome can be unambiguously linked to its 1D structure thanks to the physical properties of DNA polymers. Moreover, such 3D proximity also gives access to cell compartment information, thus opening the way for an additional approach for metagenomic binning, known as meta3C. In this work, we expand upon these methods and apply them to use cases with more and more complexity. We first improve on tools for genome assembly and demonstrate their validity with the scaffolding of Ectocarpus sp., then unveil rearrangements in joint scaffoldings of Trichoderma reesei and Cataglyphis hispanica. Lastly, we use the same approach with metagenomic binning on live mouse microbiome samples to reconstruct hundreds of genomes
Delafont, Vincent. "Diversité et implication des amibes libres dans la survie et la persistance des mycobactéries non tuberculeuses au sein d'un réseau d'eau potable." Thesis, Poitiers, 2015. http://www.theses.fr/2015POIT2278/document.
Повний текст джерелаFree-living amoebae are unicellular eukaryotes whose ecology in drinking water networks remains poorly understood. They may represent a public health concern, because of their ability to favour the presence of potentially pathogenic bacteria, among which are mycobacteria.A sampling scheme based on Paris drinking water network allowed identifying the diversity of both freeliving amoebae and their bacterial microbiome, using ribosomal RNA targeted pyrosequencing. These analyses indicated the major presence of Acanthamoeba, Vermamoeba, Echinamoeba and Protacanthamoeba genera. The microbiome was highly diverse and dominated by Pseudomonas, Stenotrophomonas, Bradyrhizobium, Sphingomonas and Pseudoxanthomonas. The coupling of physicochemical parameters to this analysis allowed underlining the importance of water origin, temperature, pH and chlorine concentration in shaping amoebal populations. Also an original endosymbiosis between V. vermiformis and a bacterium of the TM6 phylum was described. Free-living amoebae were frequently co-isolated with mycobacteria in the water network, mainly M. llatzerense and M. chelonae species. Infection experiments on A. castellanii illustrated the capacity of these species to resist and grow in presence of amoebae. Through genomics and transcriptomics approaches, several virulence factors, conserved between M. llatzerense, M. chelonae and M. tuberculosis were identified, and found to be upregulated during infection experiments. These results suggest their involvement in mycobacterial resistance to amoebal predation.Altogether, this work helped to better understand the ecology of free-living amoebae and their microbiome in drinking water networks, as well as the role of free-living amoebae in the survival and persistence of mycobacteria in such environments
Partula, Valentin. "A nutritional epidemiology study of human gut microbiota - Associations with the systemic metabolism and usual diet of the host and relationships between dietary fibers and the host’s health." Thesis, Université de Paris (2019-....), 2019. http://www.theses.fr/2019UNIP7119.
Повний текст джерелаIt is now admitted that the gut microbiota plays a key role in the health status of its human host. It is indeed fully recognized as an endocrine organ producing biologically active molecules which are integrated within human metabolism. However, comprehensive studies characterizing host-gut microbial metabolic relationships remain scarce. Numerous factors have been shown to exert a modulatory impact on the gut microbiota. Notably, diet is supposed to be a major driver, but the relationships between usual diet and the gut microbiota are not fully elucidated yet. Furthermore, many studies have suggested the implication of the gut microbiota in a wide range of disease states, such as gastrointestinal, cardio-metabolic, neuropsychiatric, etc. disorders. Thus, understanding the factors influencing the gut microbiota constitutes an active area of research. In this context, we adopted an epidemiological approach to investigate one of the largest population-based samples so far (Milieu Intérieur population, N=1,000). We notably assessed the associations between gut microbiota composition on one hand and the systemic metabolism and the usual diet of the host on the other. Finally, in the NutriNet-Santé cohort (N≈160,000), we investigated the associations between the intake of dietary fibers and the risk of a variety of chronic diseases, and described how dietary fibers are associated with the gut microbiota.Overall, our results suggest that gut bacterial features are specifically associated with certain components of the systemic metabolism of the host, and we hypothesize a substantial role of the gut-kidney axis. Besides, negative associations between food items for which a limited consumption is generally recommended (i.e. processed foods) and gut microbial features were detected. Additionally, we confirm robust inverse associations between the consumption of dietary fibers and several major chronic diseases. Mounting evidence suggests that such effects could be mediated by the gut microbiota
BARRON, PASTOR HELI JAIME. "Gut microbiome in rats: Effects of diet on community structure and host-microbiome interactions." Phd thesis, 2015. http://hdl.handle.net/1885/117702.
Повний текст джерелаLevade, Inès. "Évolution intra-hôte de Vibrio cholerae et interactions avec le microbiome intestinal." Thesis, 2020. http://hdl.handle.net/1866/25268.
Повний текст джерелаCholera is an acute diarrhoeal disease that remains a global threat to public health in countries where access to safe water and adequate sanitation cannot be guaranteed. Vibrio cholerae, the bacterial pathogen responsible for this disease, can cause a range of symptoms in infected individuals, from intense diarrhea leading to severe dehydration, to asymptomatic carriage of the bacteria. Although our understanding of cholera on a macro-epidemiological scale has been considerably improved by the development of high-throughput sequencing techniques and by advances in bacterial genomics, no studies have yet been conducted to characterize its evolution at the scale of infected individuals. Furthermore, the role of asymptomatic carriers in an epidemic and the reason behind the absence of symptoms in these infected individuals remains unknown. The main objective of this thesis is therefore to characterize the genomic diversity of V. cholerae at the level of individuals and households, but also to evaluate the potential role of the gut microbiome in the susceptibility to contract this acute enteric disease and to present severe symptoms. First, we characterize the genomic diversity of colonies isolated from symptomatic patients. The whole genome sequencing of strains from patients in Bangladesh and Haiti reveals that this diversity is detectable in the form of point mutations within hosts, but remains limited. Much of the variation detected within patients appears to be due to the gain and loss of phages and plasmids within the V. cholerae population, with occasional exchanges between the pathogen and other commensal members of the gut microbiota. These results challenge the commonly accepted assumption that V. cholerae infections are predominantly clonal, and confirm that horizontal gene transfer is an important factor in the evolution of V. cholerae. In addition, our results show that some of these variants may also have a phenotypic effect, for example by impacting biofilm formation, and can be selected within infected individuals. Next, we apply a combination of whole genome sequencing and metagenomic approaches to improve the detection of intra-host variants, both in symptomatic patients and in asymptomatic carriers. Our study shows that the metagenomic approach offers a better resolution in the detection of the diversity in the microbial population, but remains difficult to apply in asymptomatic patients, due to the low number of V. cholerae cells in these individuals. Overall, we find that the level of diversity within the intra-host bacterial population is similar between symptomatic and asymptomatic patients. We also detect the presence of hypermutator strains in some patients. In addition, while mutations in patients with hypermutator phenotypes did not appear to be driven by selection, signs of parallel evolution are detected in patients with fewer mutations, suggesting adaptive mechanisms within the host. Our results underline the power of metagenomics combined with whole genome sequencing to characterize intra-host diversity in acute cholera infection, but also in asymptomatic carriers, while identifying for the first time an hypermutator phenotype in infected patients. Finally, we are interested in factors related to susceptibility to the disease and related to the severity of symptoms. Based on a recent study using 16S rRNA amplicon sequencing to show the potential link between the intestinal microbiome and susceptibility to V. cholerae infection, our study uses metagenomic sequencing methods on the same samples from this previous study to characterize the taxonomic and functional profiles of the gut microbiome of household contacts exposed to V. cholerae. Samples are collected prior to infection of these household contacts, and used to identify predictors of symptomatic disease. Using a machine learning algorithm, we can identify species, gene families and metabolic pathways in the microbiome at the time of exposure to V. cholerae to detect potential biomarkers correlated with risk of infection and symptom severity. Our results show that the use of metagenomic sequencing improves the precision and accuracy of predictions compared to 16S rRNA amplicon sequencing. Our analyses also predict disease severity, although with greater uncertainty than the prediction of infection. Bacterial taxa from the genera Prevotella and Bifidobacterium have been identified as potential markers of protection against infection, as well as genes involved in iron metabolism. Our results highlight the power of metagenomics to predict disease progression and identify specific species and genes that could be involved in experimental tests to study the mechanisms related to the microbiome explaining potential protection against cholera.
(11186766), Geoffrey M. Williams. "Thousand Cankers Disease of Eastern Black Walnut: Ecological Interactions in the Holobiont of a Bark Beetle-Fungal Disease." Thesis, 2021.
Знайти повний текст джерелаEastern black walnut (Juglans nigra L.) ranks among the most highly valued timber species in the central hardwood forest and across the world. This valuable tree fills a critical role in native ecosystems as a mast bearing pioneer on mesic sites. Along with other Juglans spp. (Juglandaceae), J. nigra is threatened by thousand cankers disease (TCD), an insect-vectored disease first described in 2009. TCD is caused by the bark beetle Pityophthorus juglandis Blackman (Corthylini) and the phytopathogenic fungus Geosmithia morbida Kol. Free. Ut. & Tiss. (Bionectriaceae). Together, the P. juglandis-G. morbida complex has expanded from its historical range in southwest North America throughout the western United States (U.S.) and Europe. This range expansion has led to widespread mortality among naïve hosts J. nigra and J. regia planted outside their native distributions.
The severity of TCD was previously observed to be highest in urban and plantation environments and outside of the host native range. Therefore, the objective of this work was to provide information on biotic and abiotic environmental factors that influence the severity and impact of TCD across the native and non-native range of J. nigra and across different climatic and management regimes. This knowledge would enable a better assessment of the risk posed by TCD and a basis for developing management activities that impart resilience to natural systems. Through a series of greenhouse-, laboratory- and field-based experiments, environmental factors that affect the pathogenicity and/or survival of G. morbida in J. nigra were identified, with a focus on the microbiome, climate, and opportunistic pathogens. A number of potentially important interactions among host, vector, pathogen and the rest of the holobiont of TCD were characterized. The holobiont is defined as the whole multitrophic community of organisms—including J. nigra, microinvertebrates, fungi and bacteria—that interact with one another and with the host.
Our findings indicate that interactions among host, vector, pathogen, secondary pathogens, novel microbial communities, and novel abiotic environments modulate the severity of TCD in native, non-native, and managed and unmanaged contexts. Prevailing climatic conditions favor reproduction and spread of G. morbida in the western United States due to the effect of wood moisture content on fungal competition. The microbiome of soils, roots, and stems of trees and seedlings grown outside the host native range harbor distinct, lower-diversity communities of bacteria and fungi compared to the native range, including different communities of beneficial or pathogenic functional groups of fungi. The pathogen G. morbida was also associated with a distinct community of microbes in stems compared to G. morbida-negative trees. The soil microbiome from intensively-managed plantations facilitated positive feedback between G. morbida and a disease-promomting endophytic Fusarium solani species complex sp. in roots of J. nigra seedlings. Finally, the nematode species Bursaphelenchus juglandis associated with P. juglandis synergizes with G. morbida to cause foliar symptoms in seedlings in a shadehouse; conversely, experiments and observations indicated that the nematode species Panagrolaimus sp. and cf. Ektaphelenchus sp. could suppress WTB populations and/or TCD outbreaks.
In conclusion, the composition, function, and interactions within the P. juglandis and J. nigra holobiont play important roles in the TCD pathosystem. Managers and conservationists should be aware that novel associations outside the host native range, or in monocultures, intensive nursery production, and urban and low-humidity environments may favor progression of the disease through the effects of associated phytobiomes, nematodes, and climatic conditions on disease etiology. Trees in higher diversity, less intensively managed growing environments within their native range may be more resilient to disease. Moreover, expatriated, susceptible host species (i.e., J. nigra) growing in environments that are favorable to novel pests or pest complexes (i.e., the western U.S.) may provide connectivity between emergent forest health threats (i.e., TCD) and native host populations (i.e., J. nigra in its native range).
Rodrigues, Helena Maria Araújo. "The microbiome of cetaceans as a health status marker." Master's thesis, 2017. http://hdl.handle.net/1822/63946.
Повний текст джерелаNowadays, there is a growing concern about the integrity and ecological sustainability of marine environment due to several anthropogenic impacts that affect directly and strongly ocean life. Numerous aquatic species become more susceptible to diseases and infections, leading sea animals to an endangered status. Accordingly, the evaluation and monitorization of ocean ecosystem is crucial to recognize the major contributors to this imbalance as well as the at-risk populations, providing relevant information to make ecologically appropriate management decisions for both population and environmental surveillance. Cetaceans are key animals in marine habitat due to their crucial sentinel role in both disturbances and wellness of sea life. Consequently, the assessment and monitorization of their health status provides insights about aquatic health status and potential risks to ocean. Given the relevance of host-microbiome interactions, the identification of bacterial communities associated to respective hosts in distinct health and environmental contexts is extremely important. This type of studies was potentiated with the development of metagenomics approaches and progress of sequencing technologies. In this context, this work was focused on the identification of bacterial community present across fortyfour oral cavity samples from animals that differ in cause of death, occurrence local and other parameters, through DNA extraction, 16S rRNA region metagenomics sequencing and bioinformatics analysis. The results suggested a higher dominance of pathogenic genera, some of which involved in marine and human diseases. However, a considerable variation in terms of relative abundances of taxa in the target samples were also detected. This coupled with the restrict core bacteria genera may indicate that the oral microbiome of animals in study varies widely according to the corresponding animal characteristics. The PLS-DA of samples that were grouped by different metadata (species, gender, development stage, cause of death and occurrence local) indicated that these characteristics may influence the microbiome of oral cavity. Some taxa (e.g. Photobacterium and Phocoenobacter) were appointed as the genera possible involved in the microbiome discrimination, for instance, in accidental captured and diseased animals. In a near future, increasing the number of oral cavity samples analyzed the microbiome discriminations based on meta-parameters will become more statistically robust. Additionally, as the oral cavity is an easily accessible non-invasive tissue, its study is appealing due to the application in live animals, allowing a possible bio-monitorization approach based on the microbiome profile.
Atualmente há uma crescente preocupação relativamente à integridade e sustentabilidade ecológica do ambiente marinho, devido aos diversos impactos antropogénicos que afetam diretamente e fortemente a vida do oceano. Enumeras espécies aquáticas tornam-se, deste modo, mais suscetíveis a doenças e infeções, conduzindo-as a um perigo de extinção. Neste sentido, a avaliação e monitorização do ecossistema marinho é crucial para reconhecer as principais causas para o desequilíbrio, bem como identificar as populações de risco, fornecendo informações relevantes para a implementação de medidas ecologicamente apropriadas tanto para a vigilância da população como do meio ambiente. Os cetáceos são animais chave no habitat aquático devido ao seu papel sentinela em relação aos distúrbios e bem-estar da vida marinha. Consequentemente, a avaliação e monitorização do seu estado de saúde fornece igualmente perspetivas sobre o estado de saúde e potenciais riscos para o oceano. Dada a relevância das interações hospedeiromicrobioma, a identificação das comunidades bacterianas associadas aos respetivos hospedeiros em diferentes contextos ambientais e de saúde é extremamente importante. Este tipo de estudos foi potenciado pelo desenvolvimento das abordagens de metagenómica e progresso das tecnologias de sequenciação. Neste contexto, o presente trabalho foca-se na identificação das comunidades bacterianas presentes em quarenta e quatro amostras de cavidade oral, de animais com diferente causa de morte, local de ocorrência e outros parâmetros, através da extração de DNA, metagenómica e sequenciação da região de rRNA 16S e análise bioinformática. Os resultados sugeriram uma elevada prevalência de géneros patogénicos, alguns deles envolvidos em doenças marinhas e humanas. No entanto, uma variação considerável em termos de abundância relativa dos taxa bacterianos foi também detetada. Isto acoplado a um restrito microbioma core, ao nível do género, poderá indicar que o microbioma oral dos animais em estudo varia amplamente, podendo esta variação estar relacionada com as diversas caraterísticas dos animais. A PLS-DA das amostras agrupadas pelos diferentes metadados (espécie, género, estágio de desenvolvimento, causa de morte e local de ocorrência) podem indicar que estas características influenciam o microbioma da cavidade oral. Alguns géneros, como Photobacterium e Phocoenobacter, foram apontados como os possíveis causadores da discriminação do microbioma em, por exemplo, animais acidentalmente capturados e doentes. Futuramente, com o aumento do número de amostras de cavidade oral estudadas, as discriminações do microbioma, baseadas nos diferentes meta-parâmetros, tornar-se-ão estatisticamente mais robustas. Adicionalmente, como a cavidade oral é um tecido não invasivo e de fácil acesso, o seu estudo é apelativo pela aplicação em animais vivos, podendo permitir uma possível bio-monitorização baseada no perfil do microbioma.
The work presented in this thesis was performed at Molecular and Environmental Biology Centre (CBMA) on Department of Biology, specifically in Molecular Biotechnology and Molecular Genetics Laboratories, School of Sciences, University of Minho, Braga, Portugal. This work was supported by CETSENTI project (FCT/RECI/AAG-GLO/0470/2012), funded by Portuguese Foundation for Science and Technology. The work was also supported by the strategic programme UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) funded by national funds through the FCT I.P. and by the ERDF through the COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI).