Interacting Microbes, a Source for Antimicrobial Resistance Propagation

Abstract

Microbial communities are highly abundant part of our biosphere and act as a source for the vast interactional network. This web of interactions not only affects the microbial behavior but also extends its causation to the human life as well. One of the most urgent threats microbes possess globally is antimicrobial resistance. Microbial communities consist of multiple participants, their metabolites, and the surrounding environment. In this thesis contribution of bacteria, their conjugative resistance plasmids, bacteriophages, and protozoa is studied in both microbial community settings and simplified assemblies. The effect of microbial interactions to the spread of antibiotic resistant bacteria and antibiotic resistance gene carrying conjugative plasmid persistence are examined in the thesis as well as the potential of bacteriophage therapy in overcoming antimicrobial resistance crisis. One of the main findings is the effect of both protozoan predation and leakiness of antibiotic resistance mechanisms that promote antibiotic resistance plasmid persistence in the multi-trophic community rather than the surrounding antibiotic pressure. Also, the both genomic and phenotypic characteristics were evaluated, to investigate the differences in the distribution patterns of multi-drug resistant bacteria. Found drought tolerance highly associated with the epidemical successfulness status of the studied strains. The interactions between bacteria and bacteriophages were further studied and the host spectrum of tectiviruses was expanded to consider four additional genera. Also, three novel phages with possible therapeutic potential against clinical host sample were characterized both genetically and morphologically. Furthermore, this group of phages was found to interact between each other throughout the susceptibility-shifting host. For its part this thesis broadens up the vision of microbial community relevance in antimicrobial resistance prevention and cure, as well as gives an insight to overcome the crisis antimicrobial resistance cause.