Abstract
Bacteria can form dense communities called biofilms, where cells are embedded in a self-produced extracellular matrix. Exploiting competitive interactions between strains within the biofilm context can have potential applications in biological, medical, and industrial systems. By combining mathematical modelling with experimental assays, we reveal that spatial structure and competitive dynamics within biofilms are significantly affected by the location and density of the founder cells used to inoculate the biofilm. Using a species-independent theoretical framework describing colony biofilm formation, we show that the observed spatial structure and relative strain biomass in a mature biofilm comprising two isogenic strains can be mapped directly to the geographical distributions of founder cells. Moreover, we define a predictor of competitive outcome that accurately forecasts relative abundance of strains based solely on the founder cells’ potential for radial expansion. Consequently, we reveal that variability of competitive outcome in biofilms inoculated at low founder density is a natural consequence of the random positioning of founding cells in the inoculum. Extension of our study to non-isogenic strains that interact through local antagonisms, shows that even for strains with different competition strengths, a race for space remains the dominant mode of competition in low founder density biofilms. Our results, verified by experimental assays using Bacillus subtilis, highlight the importance of spatial dynamics on competitive interactions within biofilms and hence to related applications.
Highlights
Biofilms are consortia of microorganisms [1]; cells embedded in a self-produced extracellular matrix typically comprising extracellular polysaccharides, proteins, DNA, and components of lysed cells [1,2,3,4,5]
A theoretical framework of interacting bacterial strains Our mathematical model was motivated by experimental assays used to establish colony biofilms where the founding inoculum is placed on the surface of solidified nutrient agar
Significant advances in the understanding of competition dynamics within bacterial biofilms have been made in recent years [13, 14, 16,17,18,19, 26, 37]
Summary
Biofilms are consortia of microorganisms [1]; cells embedded in a self-produced extracellular matrix typically comprising extracellular polysaccharides, proteins, DNA, and components of lysed cells [1,2,3,4,5]. Many in vitro methods have been developed to study diverse biofilms. But widely used method is the colony biofilm assay. In this system, founding cells are deposited on an agar-solidified growth medium and the architecturally complex macroscale structure that develops is examined [3]. The colony biofilm assay has proven effective in revealing regulatory pathways involved in controlling biofilm formation and the production of molecules found in the biofilm matrix. It has been implemented widely across many different microorganisms [1, 3, 12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
