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metadata.dc.type: TCC
Title: Análise metagenômica da comunidade bacteriana de vacas com distúrbios reprodutivos.
metadata.dc.creator: Silva, Joana Maria Kastle.
metadata.dc.contributor.advisor1: Farias, Sávio Torres de
Abstract: Pathologies in cattle have a direct impact on production, leading to a profit decrease. Mycoplasmosis causes a range of reproductive disorders, such as contagious agalactia, mastitis, endometritis, placentitis, abortion, infertility and granular vulvovaginitis. The treatment of these pathologies can be specially challenging, driving this study to comprehend the dynamic of the bacterial communities involved in the instauration of the infection and symptoms development. To do so, samples of the genital tract from healthy cows and cows with symptoms of mycoplasmosis were collected using swabs. The genetic material was purified and extracted from these samples and, following amplification of the 16S RNA gene, sequencing of amplicon libraries was performed by the Ion Torrent Personal Genome Machine - PGM sequencing platform, using Sequencing kit 200 (Life Technologies) reagents. The sequencing results were submitted to bioinformatics programs for the development and analysis of the comparative microbial profiles. Our results show that in healthy cows the bacteria colonizing the genital tract were in totality host associated and non-pathogenic. The majority were anaerobic with a neutral pH optimal for bacterial growth. The data for the bacterial diversity in the profile with reproductive disorders suggests a significant change in the environment. In this state, anaerobic, facultative and aerobic genera are present. The pH of the genital tract of cows affected by the reproductive disorders is more acid and the presence of oxygen is an important factor, indicating an interesting shift in the ecology of the bacterial community. The total quantity and diversity of bacterial genera are higher in the affected individuals. This suggests an environmental change taking place, permitting new bacteria to colonize the genital tract niches. The relationship between anaerobic and aerobic pathogenic bacteria in the affected animals may be a case of bacterial synergy, in which different bacteria work together in the development of the infection, a condition observed in distinct animal models. Enterobacteriaceae and Bacteroides are the most numerous groups present in both the healthy and the affected states. Enterobacteriaceae are known for decreasing local pH, inhibiting neutrophil functions via succinate production, while Bacteroides difficult phagocytosis through competition with opsonins. This reduces bacteria opsonisation, hindering the immune response to infection. In the profile with reproductive disorders new families emerge, such as Pasteurellaceae, which species Histophilus somni is a known opportunistic cattle pathogen causing diseases in the respiratory, genital, nervous and circulatory systems. Arcanobacterium pyogenes, another pathogenic species with well studied ecologic relationships, Prevotella, Fusobacterium and Mycoplasma are also present, aggravating the infection. Our data suggests that the symptoms are not a result of a single pathogen, but rather a reflection of an environmental change favourable to colonization by different pathogenic bacteria that work together to cause disease.
Keywords: Análise metagenômica
Distúrbios reprodutivos
Issue Date: 20-Oct-2016
Appears in Collections:TCC - Biologia

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