🇬🇧 Bacterial aggregation and its possible role in host-microbiome interactions

Abstract

Bacterial aggregation is a widespread multicellular behaviour, yet its ecological roles and implications for pathogenesis remain poorly defined. My presentation will review the diverse mechanisms by which bacteria can form aggregates in liquid suspension, as well as some key works on aggregation in the context of a host. I will also discuss different approaches to quantitative mathematical modelling of aggregation. Finally I will present recent work from our group where we systematically characterise aggregation phenotypes in Gammaproteobacteria isolates obtained from faecal samples of critically ill patients and examine their modulation by host-derived bile acids. Contrary to suggestions in the literature that aggregation should correlate with biofilm formation and/or antibiotic tolerance or resistance, we find that aggregation in our isolates correlates negatively with biofilm formation under specific bile acid conditions, shows no association with exponential growth rate and does
not consistently confer tolerance or resistance to several tested antibiotics. I will speculate on the possible implications of this work for the ecological role of aggregation in the gut and more generally for pathogenesis and host-microbe interactions.