The Role of Mechanics on Microbial Ecology within Confined Spaces

Spatial competition is strongly driven by mechanical interactions when microbial colonies inhabit a confined and packed environment, which is crucial to the stability and diversity of the entire ecological system. However, much of the dynamics is lost in conventional bulk measurements without access to single-cell information. Hence, we developed a microfluidic-imaging system that provides spatiotemporal resolution at a single-cell level to monitor the individual behaviours and interactions of mixed populations within microscale confinied environments. In particular, we investigated the competition dynamics between two distinguishable monolayers of Escherichia coli strains equipped with various selective advantages in open-ended microchannels. We noted a bi-phasic competitive outcome: heterogenous strain coexistence and single-strain fixation, which characterizes the spatial competition. Complemented by agent-based simulations, our results reveal the significance of growth rate advantages and initial colonization abundance in shaping the competition outcomes. These results can be reproduced by a Pólya urn model, suggesting that a self-reinforcing property governs the spatial competition and that early colonization conditions largely determine the competitive outcome. We then explored the effects of morphology on the observed competitive dynamics. While our initial experimental results implied that a coccus morphology may impart a significant competitive advantage, compared to a pill shaped morphology, the simulations suggested otherwise. Last but not least, from the coexisting configurations observed within these dual-strain experiments, in conjunction with simulations and modelling, we conclude that mechanical effects can severely restrict the diversity of bacterial communities grown within confined micro-environments while promoting the emergence of heterogenous communities.

Department dc:contributor.department

Physics

Year dc:date.issued

2024

Author dc:creator

• Ma, Tianyi

Advisor dc:contributor.advisor

• Milstein, Joshua N

• Bacterial competition
• Mechanics
• Microbial communities
• Microfluidics
• Spatial constraints

Statement dc:rights

• Attribution 4.0 International

Licence dc:rights.uri

• http://creativecommons.org/licenses/by/4.0/

Handle dc:identifier.uri

http://hdl.handle.net/1807/140638

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/140638