Inter-relação entre micro-organismos presentes no rúmen de bovinos

Abstract

Ruminants do not have the ability to degrade lignocellulosic material and due to their herbivorous feeding, they developed a more complex gastrointestinal system associated with symbiosis of several microorganisms. Bacteria, as well as fungi, produce enzymes able to degrading molecules of cellulose, hemicellulose and fibers, generating among other compounds, volatile fatty acids, which are used as the main source of energy for ruminants. Therefore, the aim of this work was to analyze the occurrence of intraspecific and interspecific interactions between archaea, bacteria and fungi that inhabit the ruminal fluid of heifers. Seventeen samples of ruminal fluid were collected from Bradford heifers after the morning grazing cycle, allocated to two different pasture types. The microbial DNA was isolated and the V4 region of the rRNA 16S gene was amplified for prokaryote analysis and the ITS2 region for fungal analysis. Sequences generated from new generation sequencing were processed using the recommendations of the Brazilian Microbiome Project. Alpha diversity analyzes were calculated as well as the core microbial of both the prokaryotic and fungal communities. An interaction network was built on the Gephi platform to assess the relationships among individuals in the microbial community. A total of 131 significant correlations (p≤0.05) were found between bacteria, fungi and archaea. Calculations of eigenvector centrality suggest a greater influence of fungi in the rumen, with Sporidiobolales accounting for the greater number of positive interactions, while Ascomycota and Myriogenospora atramentosa were associated with a greater number of negative interactions. Ascomycota includes most of the pathogenic fungi of plants and animals, Myriogenospora being an endophytic species able to causing systemic infection in grasses and possibly associated with toxicity in cattle. Thus, can be concluded that in the ruminal environment there are interactions between the microorganisms present, to favor them or not. These interactions may result in a synergistic effect on the degradation of plants, increasing the digestibility or antagonistic efficiency, acting in the control of some pathogen.