Evidence of selective pressure and horizontal gene transfer among ruminal bacteria support a high prevalence of antibiotic resistance in the rumen microbiome

• Ano de defesa: 2019
• Autor(a) principal: Sabino, Yasmin Neves Vieira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Microbiologia Agrícola
• Palavras-chave em Português: Rúmen; Tetraciclina; Drogas - Resistência em micro-organismos; Ciências Biológicas
• Link de acesso: https://locus.ufv.br//handle/123456789/32215

Infections 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.