Navegando por Autor "Sabino, Yasmin Neves Vieira"
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Item Evidence of selective pressure and horizontal gene transfer among ruminal bacteria support a high prevalence of antibiotic resistance in the rumen microbiome(Universidade Federal de Viçosa, 2019-02-15) Sabino, Yasmin Neves Vieira; Mantovani, Hilário Cuquetto; http://lattes.cnpq.br/0149212201652157Infections caused by multidrug resistant (MDR) bacteria represent a therapeutic challenge both in clinical settings and in livestock production. Although antibiotics have been frequently used in cattle production, the distribution of antibiotic resistant genes (ARGs) in microorganisms that colonize the gastrointestinal tract (GIT) of ruminants is not well understood. In this study, we investigated the resistome of 435 genomes of ruminal bacteria and archaea and compared some of their phenotypes in vitro to their genotypes based on annotations of ARGs. We found that the number and classes of ARGs detected in ruminal bacteria genomes varied according to the computational tools used to search for antibiotic resistance. Genes encoding resistance to tetracycline were highly abundant/distributed in the genomes of ruminal bacteria and analysis of the d N /d S ratio indicated that the tet(W) gene in particular is under positive selective pressure. Our findings also revealed that the tet(W) gene is located in an novel integrative and conjugative element (ICE), suggesting a potential mechanism for horizontal transfer of tetracycline resistance in the rumen microbiota. Transcriptomic analyses showed that several ARGs are active in the rumen microbiome and were highly expressed in the GIT of humans. Some of the resistance phenotypes predicted in silico (31.5%) were also confirmed in vitro. Our data provide insight into the ARG profile of ruminal bacteria and reveal the potential role of mobile genetic elements in shaping the resistome of the rumen microbiome, with implications in human and animal health.Item Inhibition of Staphylococcus aureus virulence by Bacillus spp. as a potential therapy to control bovine mastitis(Universidade Federal de Viçosa, 2023-02-16) Sabino, Yasmin Neves Vieira; Mantovani, Hilario Cuquetto; http://lattes.cnpq.br/0149212201652157S. aureus is a common pathogen of humans and animals that causes long-lasting infections. In the food production sector, bovine mastitis caused by S. aureus is a common disease that severely affects milk production and quality. The treatment of bovine mastitis is challenging due to the resistance of S. aureus to many available antibiotics, and the development of new therapeutic approaches to combat antibiotic resistant bacteria has been a research priority. The objective of this study was to investigate anti-virulence compounds that inhibit hemolytic activity and biofilm formation by S. aureus, which are virulence factors associated with the severity and persistence of bovine mastitis, respectively. We evaluated the capacity of Bacillus spp., a bacterium that produces an arsenal of biologically active metabolites, to produce anti- virulence compounds. The active compounds were identified and characterized, and their mechanisms of action were evaluated. The results showed that Bacillus subtilis and Bacillus velenzesis strains were able to secrete anti-hemolytic and anti-biofilm compounds in their supernatants. The anti-hemolytic activity of Bacillus spp. against S. aureus was attributed to the production of lipopeptides. Crude extracts containing lipopeptides were able to completely abolish the hemolytic activity of S. aureus at certain concentrations. After purification, iturin was the class of lipopeptides that showed the highest anti-hemolytic activity. Molecular docking analyses revealed the ability of iturin to bind to the heptameric structure of hemolysin, both outside and inside the hemolysin pore. In turn, exopolysaccharides produced by both Bacillus species showed a dose-dependent anti-biofilm effect. At a final concentration of 1 mg/mL, exopolysaccharides were able to reduce biofilm formation by up to 83% depending on the S. aureus strains tested. The characterization of the exopolysaccharides revealed that the compounds produced by B. velezensis 87 and B. subtilis TR47II have a similar structure of approximately 30 kDa, composed mainly of glucose and mannose. The results indicated that these exopolysaccharides possibly inhibit biofilm formation mainly due to a modification of the abiotic surface characteristics. In conclusion, the study reveals for the first time the potential use of Bacillus spp. and its metabolites to control the virulence of S. aureus associated with bovine mastitis. Keywords: Staphylococcus aureus. Bovine mastitis. Bacillus spp. Anti-virulence. Biofilm. Hemolysin.