Mechanical interactions in bacterial colonies and the surfing probability of beneficial mutations

Fred D. Farrell, Matti Gralka, Oskar Hallatschek, Bartlomiej Waclaw*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Bacterial conglomerates such as biofilms and microcolonies are ubiquitous in nature and play an important role in industry and medicine. In contrast to well-mixed cultures routinely used in microbial research, bacteria in a microcolony interact mechanically with one another and with the substrate to which they are attached. Here, we use a computer model of a microbial colony of rod-shaped cells to investigate how physical interactions between cells determine their motion in the colony and how this affects biological evolution. We show that the probability that a faster-growing mutant 'surfs' at the colony's frontier and creates a macroscopic sector depends on physical properties of cells (shape, elasticity and friction). Although all these factors contribute to the surfing probability in seemingly different ways, their effects can be summarized by two summary statistics that characterize the front roughness and cell alignment. Our predictions are confirmed by experiments in which we measure the surfing probability for colonies of different front roughness. Our results show that physical interactions between bacterial cells play an important role in biological evolution of new traits, and suggest that these interactions may be relevant to processes such as de novo evolution of antibiotic resistance.

Original languageEnglish
Article number20170073
Number of pages13
JournalJournal of the Royal Society. Interface
Issue number131
Early online date7 Jun 2017
Publication statusPublished - 30 Jun 2017

Keywords / Materials (for Non-textual outputs)

  • biological evolution
  • bacterial colony
  • interactions
  • surfing probability
  • roughness


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