Diversity of viruses present in cattle rumen and in genomes of Ralstonia sp species complex

• Ano de defesa: 2019
• Autor(a) principal: Souza, Flávia de Oliveira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Microbiologia Agrícola
• Palavras-chave em Português: Diversidade genética; Vírus - Ecologia; Ralstonia; Rumen - Microbiologia; Microbiologia Agrícola
• Link de acesso: https://locus.ufv.br//handle/123456789/32213

Viruses are microorganisms present in all environments and can infect all types of organisms. Viral infection affects the dynamics and characteristics of its hosts, depending on the type of infection cycle the virus uses. Efforts have long been made to discover and characterize new viruses through techniques such as filtration, tissue culture, electron microscopy, serology, and vaccination under laboratory conditions. Advances in nucleic acid sequencing techniques, bioinformatics and independent laboratory culture maintenance techniques such as metagenomics have been used in studies to discover and characterize viruses in various environments. The ecological relationship between viruses and a given host group has been accessed through bioinformatics, identifying virus- derived sequences in already sequenced bacterial genomes. This analysis is possible because some bacteria-infecting viruses can integrate into the bacterial genome and remain in the form of a pest, replicating their genome along with the bacterial genome. In this sense, the growing number of complete sequences of bacterial genomes available in databases has made it possible to search for evidence of viruses integrated into these genomes on a global scale. Ralstonia solanacearum is the main phytopathogenic bacterium that causes bacterial wilt disease, capable of infecting about 200 cultures, distributed in about 50 different botanical families. In addition, R. solanacearum is recognized as a group of bacteria with genetic diversity, where strains can be phenotypically subdivided into four phylotypes. Despite current efforts to isolate infecting viruses, little is known about the occurrence and composition of pests in the genomes of Ralstonia spp. However, the importance of viruses in a complex environment has also been the focus of studies. In fact, viral diversity in different ecosystems has been accessed through independent laboratory culture methods and without the need to know the host of these viruses. The main environments surveyed are seawater, soil, feces and intestines of human and mammalian animals. The rumen is a component of the gastrointestinal system of ruminant animals that has as one of its main characteristics a complex population of microorganisms residing in this environment. Ruminate animals are unable to produce enzymes to degrade the fiber ingested in food. Ruminal microorganisms, unlike animals, produce these enzymes and, therefore, are directly responsible for obtaining energy from the animal and, consequently, for its health and profitability. Therefore, rumen microbiota is the focus of research, but studies on rumen viroma are still scarce. Due to the complex relationships between viruses and their hosts, either in relation to a specific group of bacteria, such as plant pathogens, or in symbiotic environments such as bovine rumen, we proposed to analyze the presence of virus derived sequences in the species complex genomes. Rasltonia solanacearum (RSC) available from the National Center for Biotechnology Information (NCBI) database. We also accessed the viroma of two dairy cows from the Federal University of Viçosa and were able to isolate the first mimivirus-like virus from these rumen samples. Keywords: Viral Diversity. Viral Ecology. Rasltonia species complex. Rumen virome.