Cooperation and conflict in microbial biofilms
Authored by Kevin R Foster, Joao B Xavier
Date Published: 2007
DOI: 10.1073/pnas.0607651104
Sponsors:
National Institute of General Medical Sciences Center of Excellence
Platforms:
No platforms listed
Model Documentation:
Other Narrative
Flow charts
Mathematical description
Model Code URLs:
Model code not found
Abstract
Biofilms, in which cells attach to surfaces and secrete slime (polymeric
substances), are central to microbial life. Biofilms are often thought
to require high levels of cooperation because extracellular polymeric
substances are a shared resource produced by one cell that can be used
by others. Here we examine this hypothesis by using a detailed
individual-based simulation of a biofilm to investigate the outcome of
evolutionary competitions between strains that differ in their level of
polymer production. Our model includes a biochemical description of the
carbon fluxes for growth and polymer production, and it explicitly
calculates diffusion-reaction effects and the resulting solute gradients
in the biofilm. An emergent property of these simple but realistic
mechanistic assumptions is a strong evolutionary advantage to
extracellular polymer production. Polymer secretion is altruistic to
cells above a focal cell: it pushes later generations in their lineage
up and out into better oxygen conditions, but it harms others; polymer
production suffocates neighboring nonpolymer producers. This property, analogous to vertical growth in plants, suggests that polymer secretion
provides a strong competitive advantage to cell lineages within
mixed-genotype biofilms: global cooperation is not required. Our model
fundamentally changes how biofilms are expected to respond to changing
social conditions; the presence of multiple strains in a biofilm should
promote rather than inhibit polymer secretion.
Tags
Competition
Communication
Model
microorganisms
bacteria
Altruism
social evolution
Strategies
Communities
Pseudomonas-aeruginosa