Prokaryotic genomes evolve via horizontal gene transfer (HGT), mutations, and rearrangements. HGT is a mechanism that plays a significant role in prokaryotic evolution and leads to biodiversity in nature. One of the important components of HGT is the genomic island (GI) which is a subsequence of the genome created by HGT. This research aims to identify the structures of the prokaryotic GIs that have a fundamental role in the adoption of prokaryotes and the impact of the species on the environment. Previous computational biology research has focused on developing tools that detect GIs in prokaryotic genomes, while there is little research investigating GI structure. This research introduces a novel idea that has not yet been addressed intensively, which is identifying additional structures of the GIs in prokaryotes. There are two main directions in this research used to study the prokaryotic GIs structure from each different perspective. In the first direction, the aim is to investigate GI patterns and the existence of biological connections across bacterial phyla in terms of GIs on a large scale. This direction mainly aims to pursue the novel idea of connecting GIs across prokaryotic and phage genomes via patterns of protein families across many species. A pattern is a sequence of protein families that is found to frequently occur in the genomes of a number of species. Here the large data set available from the IslandViewer4 database and protein families from the Pfam database have been combined. Furthermore, implementing a comprehensive strategy to identify patterns that makes use of HMMER, BLAST, and MUSCLE; also implement Python programs that link the analysis into a single pipeline. Research results demonstrate that related GIs often exist in multiple species that are not evolutionarily related and indeed may be from multiple bacterial phyla. Analysis of the discovered patterns led to the identification of biological connections among prokaryotes and phages through their GIs. A connection is an HGT relation represented as a pattern that exists in a phage and a number of prokaryotic species. These discovered connections suggest quite broad HGT connections across the bacterial kingdom and its associated phages. In addition, these connections provide the basis for additional analysis of the breadth of HGT and the identification of individual HGT events that span bacterial phyla. Moreover, these patterns can suggest the basis for discovering the specific patterns in pathogenic GIs that could play a crucial role in antibiotic resistance. The second direction aims to identify the structure of the GIs in terms of their location within the genome. Prokaryotic GIs have been analyzed according to the genome structure that they are located in, whether it be a circular or a linear genome. The analysis is performed to study the GIs' location in relation to the oriC, investigating the nature of the distances between the GIs, and determining the distribution of GIs in the genome. The analysis has been performed on all of the GIs in the data set. Moreover, the GIs in one genome from each species and the GIs of the most frequent species are in the data set, in order to avoid bias. Overall, the results showed that there are preferable sites for the GIs in the genome. In the linear genomes, they are usually located in the origin of replication area and terminus, and in the circular genomes they are located in the terminus. / Doctor of Philosophy / Prokaryotes are one of the most abundant species on earth that play an essential role in naturally shaping the planet and its life. This research aims to identify the structure of a component in these species that has a fundamental role in the adoption of prokaryotes and the impact of the species on the environment. This component is a part of the genome named the genomic island (GI). This dissertation aims to identify the structure of the GIs in two different ways that have not yet been addressed extensively. The first direction aims to discover patterns in the GIs and then use them to bring to light biological connections between prokaryotic and bacteriophages. In this direction, a comprehensive strategy has been utilized to identify patterns and connections. This strategy uses several tools such as BLAST, HMMER, and MUSCLE. Furthermore, Python programs that link the analysis into a single pipeline have been implemented. In the second direction, an investigation has been performed to understand the nature of the GIs' locations within the genome. This direction addresses three different analysis techniques to achieve its target. The three analyses are studying the GIs' location in relation to the origin of replication, investigating the nature of the distances between the GIs, and discovering the location distribution of GIs in the genome. The analysis is performed on linear genomes and circular genomes separately. In each group of GIs, the data set has been utilized to see the results from different perspectives. The overall analysis in both directions relived several findings. In the first direction, the discovered patterns merit deep investigation based on the possibility that they are related to diseases. In addition, in prokaryotic genomes, there are specific sites where the GIs can be frequently seen that need further search to understand the relation between the GIs' location and the content of the GI in terms of proteins.

Pantoea stewartii subsp. stewartii is a bacterial phytopathogen that causes the disease Stewart's wilt in corn. The insect vector Chaetocnema pulicaria, the corn flea beetle, transmits P. stewartii into corn plants through wounds in the leaves. The bacteria can then move to the xylem of the plant where they form a biofilm that inhibits the flow of water. A previous in planta RNA-Seq study resulted in the selection of lrp as a gene of interest for further analyses. A reverse genetics approach was used for the creation of a strain containing the in-frame deletion of lrp, as well as a revertant strain. The strain with the deletion of the lrp gene showed reduced motility and capsule formation when in vitro assays were conducted. It has previously been demonstrated that these characteristics are both important for the bacteria's ability to form a biofilm in the xylem of corn plants and produce disease symptoms. The in planta virulence and competition assays demonstrated that the lrp gene deletion also results in reduced disease symptoms in infected corn plants, as well as an inability to outcompete wildtype P. stewartii in xylem colonization. In a bioinformatics approach, the transcriptional regulator Lrp of P. stewartii was present in the same node of the phylogeny as homologues from other closely related phytopathogens. This demonstrates that Lrp from P. stewartii and such homologues have evolved from a recent common ancestral gene. Examining the genomic islands present in P. stewartii, it is possible to begin to predict where some of the genes which have functions involved in plant colonization may have originated. Overall, the results collected from the studies in this thesis contribute to improving understanding of how P. stewartii is successful at colonizing the xylem of corn plants and cause disease. This research could result in the development of methods to decrease crop susceptibility to infection with P. stewartii. / Master of Science / Stewart's wilt is a disease of corn plants caused by the bacterium Pantoea stewartii subsp. stewartii via the insect vector Chaetocnema pulicaria, the corn flea beetle. This infection has proven to be costly as it impacts the health of corn crops and impedes the export of corn seeds from varieties that are susceptible to infection by P. stewartii. The focus of the research conducted for this thesis has been on learning more about how specific P. stewartii genes impact the ability of the bacterium to colonize corn plants and cause Stewart's wilt disease symptoms. The information collected from this study is important for developing a better understanding of how wilt disease-causing pathogens are able to successfully infect plants, as well as for developing future treatments to prevent further infection of corn plants. In addition, preliminary bioinformatics work has shown that some of the P. stewartii genes of interest share a common ancestor with select genes from other known plant pathogens. Additional preliminary bioinformatics work on regions of the DNA called genomic islands has revealed where some genes of importance to the bacterium's ability to colonize plants may have originated. Overall, the work presented in this thesis contributes to improving our understanding of the roles that different parts of the P. stewartii genome have in allowing the bacterium to successfully colonize and cause disease in corn plants.

Avec l'accroissement du nombre de génomes séquencés, l'organisation de ces données brutes et des données dérivées, l'extraction de l'information et des connaissances associées défie l'imagination. La notion de voisinage a été d'abord été introduite pour l'organisation des données dans des bases de données relationnelles. Pour extraire des informations pertinentes à partir de données massives, différents types de voisinages ont été étudiés ici. Tout d'abord, avec l'analysedes correspondances (CA) et en utilisant le regroupement supervisé ("model clustering" MBC), la proximité mutuelle des éléments formant deux entités biologiques centrales, les gènes (codant les protéines) et les acides aminés a été analysée. Nous montrons par exemple que les protéines de Psychromonas ingrahamii, bactérie psychrophile extrêmes, sont regroupées en six classes, et qu'il y a une forte opposition entre le comportement de l'asparagine (N) et des acides aminés sensibles à l'oxygène, ce que nous expliquons en terms de résistance au froid. Ensuite, nous avons analysé la répartition entre les îlots génomiques (GI) et le squelette du génome de base à partir d'une nouvelle méthode combinant composition en bases et en gènes, caractéristiques GI et de briser les synténies. L'application de cette approche à E. coli et B. subtilis a révélé que cette nouvelle méthode permet d'extraire certaines régions significative, non publiées auparavant.Enfin, pour illustrer un voisinage fin, la régulation de l'expression d'un gène et son évolution, nous avons étudié la relation entre les régions en amont du gène et la zone codante du gène thrS de façon approfondie. Nous avons constaté que ces deux régions associées à un gène, se sont comportés différemment dans l'histoire évolutive. Certaines des régions en amont porteuses de la fonction non-essentielle de régulation (qui contrôle l'expression de gène) ont évoluédifféremment de la région codante. / With more and more genomes being sequenced, the organization of those raw data and the derived data, the extraction of information and knowledge from these data has become a challenge. A key concept in this field is that of the neighborhood, especially with respect to the organization of data in relational databases. To extract information from bulk data, different kinds of neighborhoods were studied and each show interesting results in current study. .Firstly, through the Correspondence Analysis (CA) and later Model Based Clustering (MBC), two kinds of neighbors i.e. the genes (proteins) and amino acids were analyzed respectively, and it was found that proteins from Psychromonas ingrahamii are clustered into six classes, and there is strong opposition between asparagine (N) and the oxygen-sensitive amino acids. Secondly, the relationship between genomic islands and core genome (i.e. two closely linked neighbors withlarge range on the chromosome) was studied by a new method combining composition, GI features and synteny break. On applying to E. coli and B. subtilis it was revealed that this new method can extract some meaningful regions not published before. Thirdly, the relationship between upstream and coding regions of thrS gene (i.e. a case for two closely linked neighbors with small range on the chromosome) was studied extensively. It was found that these two regions associated to one gene, behaved differently in the evolutionary history.. Some of the upstream regions bearing non-essential function (i.e. regulation of gene expression) evolved more slowly than the coding region.

Les bactéries du genre Streptomyces produisent de nombreux métabolites secondaires, dont certains possèdent des propriétés intéressantes en agriculture et en pharmaceutique. Avec le développement de la génomique, de nombreux outils bioinformatiques de recherche de groupes de gènes du métabolisme secondaire ont été développés au cours de la dernière décennie pour explorer les génomes. Ces outils sont basés sur la recherche de similarité de séquences et de ce fait, les clusters atypiques, constitués de gènes non caractérisés, ne peuvent être détectés par ces approches. L'isolement de tels clusters nécessite donc la mise en œuvre de nouvelles stratégies. La comparaison d’espèces d'Actinomycetes proches a révélé que les îlots génomiques, régions présentes dans un seul génome, sont très souvent enrichis en gènes du métabolisme secondaire. Nous avons participé (en collaboration avec les équipes d’Olivier Lespinet et de Pierre Leblond et Bertrand Aigle) au développement d’un outil, Break Viewer, permettant de localiser les îlots génomiques en comparant des génomes proches de Streptomyces. Cet outil a permis l'identification d'un îlot non détecté par les approches classiques, îlot dont l'étude a montré qu'il contenait un groupe de gènes du métabolisme secondaire. L’étude de ce groupe de gènes a montré qu'il dirige la synthèse de trois composés, le produit majoritaire étant le sphydrofurane. Une analyse fonctionnelle du cluster sphydrofurane a permis de déterminer les gènes impliqués dans la biosynthèse et la régulation de la biosynthèse du sphydrofurane et de proposer un modèle préliminaire pour la biosynthèse de ce métabolite. / Streptomyces are soil-dwelling bacteria that produce numerous secondary metabolites, some of which have interesting properties in agriculture and pharmaceuticals. With the development of genomics, many bioinformatics tools to search genomes for secondary metabolism gene clusters have been developed over the last decade. These tools are based on sequence similarity searches and therefore atypical clusters, consisting of uncharacterized genes, cannot be detected by these approaches. The isolation of such atypical clusters therefore requires the implementation of new strategies.Comparing closely related Actinomycetes species revealed that genomic islands (regions that are present in one genome only), are often enriched in secondary metabolite genes. We participated (in collaboration with the team of Olivier Lespinet and the team of Pierre Leblond and Bertrand Aigle) to the development of a new tool, Break Viewer, to locate genomic islands by comparing the genomes of closely related Streptomyces. This tool allowed the identification of an island, undetected by conventional approaches, island whose study showed that it contained a secondary metabolism gene cluster. The study of this cluster has shown that it directs the synthesis of three compounds, the major product being sphydrofuran. A functional analysis of the sphydrofuran gene cluster allowed us to identify the genes involved in the biosynthesis and regulation of sphydrofuran and to propose a preliminary model for the biosynthesis of this metabolite.

Thesis (Ph. D.)--Virginia Commonwealth University, 2007. / Prepared for: Dept. of Microbiology and Immunology . Bibliography: leaves 130 - 137 . Also available online via the Internet.

Les liens entre la diversité et l'adaptation des populations bactériennes à leur environnement constituent une problématique importante en écologie microbienne. L'accès à de nombreux génomes permet aujourd'hui des avancées intéressantes dans ce domaine. Plusieurs souches du genre Thiomonas et appartenant à la même espèce, Tm. arsenitoxydans 3As et Tm. spp. CB1, CB2, CB3 et CB6, ont été isolées d'un drainage minier acide (DMA) à Carnoulès (Gard). La comparaison de leur génome a permis d'affiner leur phylogénie et de mettre au jour des différences de contenu génétique liées à des îlots génomiques. Certaines de ces différences ont été corrélées expérimentalement avec des différences fonctionnelles concernant l'oxydation de l'arsénite (As(III)), la dégradation de l'urée et la biosynthèse de biofilm, et confèrent potentiellement un avantage sur le site (meilleure résistance à l'As(III), précipitation des métaux et augmentation du pH, protection des cellules). La comparaison de la synténie des génomes de Tm. arsenitoxydans 3As avec Tm. sp CB2 et Tm. intermedia K12 (non isolée de ce DMA) a montré que le génome de Tm. sp. CB2 a subi plusieurs remaniements importants. Ces types de réarrangements pourraient être en partie à l'origine de l'apparition de variants "super-résistants" à l'As(III) dans la population. En particulier, plusieurs copies d'un élément intégratif et conjugatif portant l'opéron aioBA codant l'arsénite oxydase ont été détectées chez deux variants, ce qui pourrait en partie expliquer leur résistance accrue à l'As(III). La proportion de variants est plus importante en présence d'As(III) au sein des biofilms, et des données de transcriptomique ont en effet montré que ces remaniements seraient en partie causés par des systèmes de réparation de l'ADN suite à des dommages liés au stress oxydant induit par l'As(III). Le développement en biofilm et la présence d'As(III) modulerait donc la flexibilité génomique et le potentiel adaptatif de Tm. sp. CB2. Ces données suggèrent que cette souche, avec Tm. sp. CB3, possèdent un génome visiblement plus flexible que les autres. Les souches Tm. arsenitoxydans 3As et Tm. spp. CB1 et CB6, contrairement à Tm. spp. CB2 et CB3, forment un groupe distinct d'un point de vue phylogénétique et fonctionnel ("groupe 3As"), suggérant qu'elles occupent une niche écologique spécifique et pourraient constituer un écotype. La population de Thiomonas de ce DMA serait donc composée d'au moins un écotype stable et de souches au génome plus instable, dont le potentiel adaptatif plus important serait influencé par l'As(III) et le développement en biofilm. / Understanding the link between diversity and adaptation in natural bacterial populations represents an important issue in microbial ecology. The amount of whole genome sequencing data currently available has allowed for interesting advances in this field. Several strains from the genus Thiomonas belonging to the species, Tm. arsenitoxydans (3As) and Tm. spp. (CB1, CB2, CB3 and CB6), were isolated from the acid mine drainage (AMD) at Carnoulès (Gard, France). Comparison among genomes allowed for a better definition of their phylogenetic relationships and highlighted differences in genetic content, which is essentially due to the presence of genomic islands. Some of these differences were experimentally correlated with functional traits concerning arsenite oxidation, urea degradation, and biofilm biosynthesis, and are potentially beneficial in situ (leading to an enhanced resistance to arsenite (As(III)), metal precipitation, and an increase in pH, ultimately protecting cells). The comparison of genome synteny of Tm. arsenitoxydans 3As, Tm. sp CB2, and Tm. intermedia K12 (not isolated from this AMD) show several important genomic rearrangements exist in Tm. sp CB2. This type of rearrangements could be involved in the emergence of arsenite "super-resistant" variants in the Tm. sp CB2 population. In particular, several copies of an integrative and conjugative element (ICE) containing the aioBA operon coding arsenite oxidase were detected in the genomes of two variants, which could explain their higher levels of resistance to As(III). The percentage of variants in biofilm culture is higher when grown in the presence of As(III), and transcriptomic data suggests that genomic rearrangements probably occurred through DNA repair systems following damage caused by As(III) induced oxidative stress. Therefore, biofilm development and As(III) appear to allow for the adaptation of Tm. sp. CB2 genome flexibility and evolutionary potential. These data suggest that CB2 and Tm. sp. CB3 have more flexible genomes than the other strains. Tm. arsenitoxydans 3As and Tm. spp. CB1 and CB6 form both a phylogenetic and functional cluster ("3As group") suggesting that they occupy a specific ecological niche and therefore could represent an ecotype of the genus Thiomonas. The Thiomonas population from the Carnoulès AMD might therefore consist of at least one stable ecotype as well as other strains with more instable genomes, whose higher adaptive potential could be affected by As(III) and biofilm development.

Les bactéries du genre Nocardia sont des Actinobactéries filamenteuses. Ces microorganismes sont saprophytes du sol. Les infections à Nocardia ou nocardioses se manifestent dans la majorité des cas (60%) par des infections pulmonaires et plus rarement par des infections cérébrales. La souche Nocardia cyriacigeorgica GUH-2 à causé la mort d’un patient dans les années 70. Des études sur cette souche ont montré qu’elle avait un haut pouvoir pathogène et qu’elle était capable dans certaines conditions de déclencher chez la souris et les primates le développement de troubles moteurs similaires à ceux observés dans la maladie de Parkinson. Afin d’appréhender l’implication de l’espèce pathogène opportuniste N. cyriacigeorgica dans l’une des plus importantes maladies neurodégénératives du 21ème siècle, le séquençage du génome de la souche N. cyriacigeorgica GUH-2 à été entrepris. Il a permis l’identification d’un grand nombre de gènes liés à la virulence et à la résistance aux antibiotiques ainsi que l’identification d’ilots génomiques et de séquences d’insertions reflétant une plasticité plus grande que celle qui était décrite pour ce genre bactérien. L’étude de groupements de gènes impliqués dans la production de métabolites secondaire a montré que ces molécules pourraient être responsables des propriétés neurodégénératives de la souche. L’espèce de N. cyriacigeorgica étant retrouvée fréquemment en clinique sans que son réservoir naturel n’ai été mis en évidence à ce jour, la mise au point de marqueurs de détection génétique a été réalisé afin de permettre la recherche de la niche écologique de cette espèce mais également de faciliter le diagnostic des nocardioses. / Nocardia are filamentous-growing Gram-positive soil saprophytes that belong to Actinobacteria. Nocardial infections or nocardiosis are lung infections in most of the cases (60%) and more rarely brain infections. Nocardia cyriacigeorgica strain GUH-2 had cause the death of a patient in the 70's. Studies have shown that its strain had a high pathogenicity and the ability to trigger the development of motor disorders in mice and primates similar to those seen in Parkinson's disease.In order to understand the involvement of this opportunistic pathogen in one of the major neurodegenerative diseases of the 21st century, the genome of the strain N. cyriacigeorgica GUH-2 was sequenced. It allowed the identification of a large number of genes related to virulence, antibiotic resistance and the identification of genomic islands and insertion sequences reflecting a greater plasticity that it was previously described for this bacterial genus. The study of clusters of genes involved in the production of secondary metabolites showed that these molecules could be responsible for the neurodegenerative properties of the strain. N. cyriacigeorgica species is frequently encountered in the clinic without its natural reservoir has been identified to date. The development of genetic markers for detection was carried out to allow the search for the habitat of this species but also to facilitate the diagnosis of nocardiosis.

Made available in DSpace on 2014-08-20T14:37:53Z (GMT). No. of bitstreams: 1 dissertacao_tanise_fortes.pdf: 3529801 bytes, checksum: 88734c926a2abf7729f24c5ee75649d1 (MD5) Previous issue date: 2013-07-25 / Brazil has one of the largest commercial heard of the world and it is a great beef exporter. Meanwhile, for the consolidation of Brazilian exportation of meat in natura and its derivatives it is necessary that the products have food safety. Among the microorganisms used as indicators of food security, Salmonella has a special attention because it causes severe diseases to animals and humans. This study was developed with the objective to isolate Salmonella during the cattle slaughter in a state inspection slaughterhouse located in the city of Pelotas, Rio Grande do Sul. A hundred and fifty samples were collected from three different points of slaughter: leather of the animal after bleeding (P1), the carcass after evisceration (P2) and cecum contents (P3). The isolates were tested for their antimicrobial susceptibility in vitro using amoxicillin, ampicillin and ciprofloxacin. As results, two (1,33%) strains were isolated from bovines and classified as Salmonella. No strain was isolated from buffalos. The two isolates were susceptible to amoxicillin and ciprofloxacin. Besides the investigation of the presence of Salmonella in the cattle flowchart, a review about Salmonella pathogenicity islands (SPI) was performed. According to the results, we conclude that there is the risk of incorporating the bacteria at the slaughter time by the ruminants, contaminating the carcasses. The implementation and maintenance of means to control the quality in the market facilities are important to prevent or reduce the health risk to employees and consumers. / O Brasil possui um dos maiores rebanhos de ruminantes do mundo e destaca-se como um grande exportador de carne. Entretanto, para que a exportação brasileira de carne in natura e seus derivados seja consolidada é importante que o produto tenha segurança alimentar. Entre os micro-organismos usados como indicadores de segurança alimentar, Salmonella se destaca por causar muitas doenças em animais e humanos. Este estudo foi realizado com o objetivo de isolar Salmonella durante o abate de ruminantes em um frigorífico sob inspeção estadual, localizado na cidade de Pelotas, Rio Grande do Sul, que utiliza medidas para o controle de qualidade. Cento e cinquenta amostras foram coletadas de três pontos diferentes do abate: couro do animal após a sangria (P1), carcaça após a evisceração (P2) e conteúdo cecal (P3). Os isolados foram testados quanto à suscetibilidade antimicrobiana in vitro usando amoxicilina, ampicilina e ciprofloxacina. Como resultados, duas (1,33%) cepas foram isoladas de bovinos e classificadas como Salmonella. Nenhuma cepa foi isolada de búfalos. Os dois isolados apresentaram suscetibilidade à amoxicilina e à ciprofloxacina. Além da investigação da presença de Salmonella no fluxograma de ruminantes, foi realizada uma revisão sobre ilhas de patogenicidade em Salmonella (SPI). De acordo com os resultados, conclui-se que existe o risco da bactéria ser incorporada na linha de abate pelos ruminantes e, dessa forma, provocar a contaminação das carcaças. A implementação e a manutenção de medidas para o controle de qualidade nos estabelecimentos são importantes para prevenir ou reduzir o risco à saúde dos funcionários e consumidores.

Die genomische Insel (GI) FhaGI 1 des Stammes Francisella hispaniensis (Fhis) AS02 814 kann sowohl in die tRNAVal integriert als auch als episomale Form vorliegen und kodiert für einen putativen Prophagen. Im Rahmen dieser Arbeit konnte durch Verwendung synthetisch hergestellter, verkürzter Varianten von FhaGI-1 gezeigt werden, dass die GI auf andere Francisella Spezies übertragbar ist. Die ortsspezifische Integration und Exzision der GI sind Integrase-abhängige Prozesse, die durch weitere regulatorische Gene beeinflusst werden. Die Identifizierung der GI FphGI 1 in drei F. philomiragia-Stämmen zeigt, dass die tRNAVal als Integrationsort für GIs in Francisella dient. Die vermutlich nicht funktionale Integrase von FphGI 1 ist wahrscheinlich die Ursache für das Fehlen einer episomalen Form der GI. Das Vorhandensein von GIs in Francisella liefert einen Hinweis darauf, dass horizontaler Gentransfer zwischen verschiedenen Francisella Spezies möglich ist. Auf Grundlage von FhaGI 1 wurden zwei Varianten eines Francisella- Phagenintegrationsvektors (pFIV1-Val und pFIV2 Val) generiert. Der FIV Teil der Vektoren bildet eine zirkuläre, episomale Form, die nach der Transformation in verschiedene Francisella Spezies ortspezifisch in die tRNAVal integriert. Es konnte gezeigt werden, dass die Vektoren für die Expression von Reportergenen sowie die Komplementation von Francisella Deletionsmutanten geeignet sind. Sie sind sowohl in vitro als auch während der Infektion von Wirtszellen ohne Selektionsdruck stabil und zählen zu den low-copy-Vektoren. Damit erweitern die FIV-Vektoren das Repertoire der vorhandenen Werkzeuge zur genetischen Manipulation von Francisellen. Da der Stamm Fhis AS02 814 für Untersuchungen nicht zur Verfügung stand, wurde FhaGI 1 synthetisch in zwei Hälften hergestellt, die jedoch bisher nicht zusammengeführt werden konnten. Damit ist eine Aussage darüber, ob es sich bei FhaGI 1 tatsächlich um einen funktionalen Prophagen handelt, bis jetzt nicht möglich / The genomic island (GI) FhaGI 1 of strain Francisella hispaniensis (Fhis) AS02 814 can exist as a circular episomal form or integrated into the tRNAVal gene and codes for a putative prophage. In this work small-sized variants of FhaGI 1 were used to show that the GI can be transferred to other Francisella species. The site-specific integration and excision of the GI are integrase-dependent processes that are influenced by further regulatory genes. The identification of the GI FphGI 1 in three F. philomiragia strains shows that the tRNAVal gene serves as an integration site for GIs in Francisella. The integrase of FphGI 1 is probably non-functional and hence presumably the reason for the missing episomal form of the GI. The presence of GIs in Francisella might be an indication that horizontal gene transfer between different Francisella species could be possible. Two variants of a Francisella phage integration vector (pFIV1 Val and pFIV2 Val) were successfully constructed based on FhaGI 1. The FIV Val part of the vectors integrates site-specifically into the tRNAVal after transformation into different Francisella species. It was demonstrated that the vectors can be used for the expression of reporter genes as well as for the complementation of Francisella deletion mutants. They remain stable without selective pressure during in vitro growth and during the infection of host cells and fall into the group of low-copy-vectors. The FIV Val vectors expand the repertoire of tools that can be used for the genetic manipulation of Francisella. As strain Fhis AS02 814 could not be obtained for further analysis, FhaGI 1 was synthetically generated in two halves which could not be joined so far. Consequently, it is not possible to state whether FhaGI 1 actually codes for a functional prophage.