The structure of pairwise competition is responsible for sudden regime shifts in a microbe-plasmid model

Abstract

Plasmids play a crucial role in bacterial communities by facilitating the horizontal transfer of genetic material, particularly genes that confer resistance to different stressor agents. In this work, we introduce a microbe-plasmid model to study the conditions under which a plasmid-carrying bacterial strain can invade its corresponding plasmid-free counterpart, as well as those under which it can be eradicated from the population through potential intervention strategies. We reveal the variety of dynamic regimes of the model depending on the parameter values. In particular, we show that a heterogeneous structure of the competition between the two strains drives the possibility of coexistence of stationary states (i.e. bistability) which creates conditions for sudden regime shifts and hysteresis. We explore the implications of our results for the potential eradication of plasmid-mediated antibiotic resistance.