PhD defence Siyu Mei
Siyu Mei (GREEN)
Promotor: Prof. J. Falcao Salles; copromotores: Dr T. Hackl, Dr S. Lequime
A missing link in microbial ecology?
Unpacking the soil mobilome over a century-long soil chronosequence
Microbial communities are fundamental to healthy ecosystems, yet we have a limited understanding of how they adapt to environmental changes. This thesis investigates a "hidden force" driving this adaptation: Mobile Genetic Elements (MGEs) exchanged via Horizontal Gene Transfer (HGT). These mechanisms allow microbes to rapidly acquire new traits, essential for survival under pressure. Using a century-long soil chronosequence as a model, this research explores how these genetic engines shape microbial resilience. The study first examines the spread of antimicrobial resistance (AMR) within a One Health framework, highlighting the impact of human activity on natural environments. It then focuses on the bacterial genus Pseudomonas, analyzing how horizontally acquired genes evolve during soil formation. Finally, the thesis compares extracellular carriers of genetic material—specifically virus-like particles (VLPs) and extracellular vesicles (EVs). A key finding is a proposed "dual-mode" framework: VLPs act as vectors for genetic innovation, while EVs play a conservative role in maintaining genomic stability. By balancing innovation and conservation, these mechanisms enable microbial communities to thrive in developing ecosystems. This research offers vital insights into the genomic mechanisms underlying microbial resilience