Characterization of probiotic strains for use as alternatives to antibiotics in avian production

Identifier:  TFG:3007

Handle: https://hdl.handle.net/20.500.11797/TFG3007

Authors:  Sáez Fuertes, Laura

Abstract:
In the last few years, not only the meat consumption has been increased but also the use of antibiotics, improving animal performance. At the same time, this fact is promoting the appearance of antimicrobial resistance. The EU banned the use of antibiotics as growth promoters (2006), generating an intense search for alternative products with beneficial effects similar to antibiotics, among which probiotics stand out. Recent advances in mass sequencing make complete genetic analysis of bacterial strains economically feasible, allowing the discernment of specific genes that confer probiotic capacity. The objective of this work is to develop a novel tool, based on the characterization of bacterial genomes, that facilitates the detection of new candidate probiotic strains by identifying relevant genes in probiotics effects. To create this tool, two known probiotic strains (both Bacillus subtilis) have been genetically characterized by targeted and massive analyses. The targeted approach has been based on the detection of known genes that confer probiotic capacity. Genes have been identified for resistance to antibiotics, synthesis of essential compounds, enzymes, bacteriocins, proteins for adhesion to the epithelium, and resistance to the gastric acid environment. The massive approach has focused on the search for minority genes present in the known Bacillus to identify if they are the ones that confer the differential probiotic capacity demonstrated in vivo. After these analyzes, it has been possible to generate a database of genes relevant to probiotic effects, allowing the characterization of new candidate strains after their sequencing. In order to validate this tool, future metatranscriptomic and in vivo studies will be necessary.