Multispecies phase diagram reveals biophysical principles of bacterial biofilm architectures

Bacterial biofilms are among the most abundant multicellular structures on Earth and play essential roles in a wide range of ecological, medical, and industrial processes. However, general principles that govern the emergence of biofilm architecture across different species remain unknown. Here, we combine experiments, simulations and statistical analysis to identify shared biophysical mechanisms that determine biofilm architecture development at the single-cell level, for the species Vibrio cholerae, Escherichia coli, Salmonella enterica, and Pseudomonas aeruginosa. Our data-driven analysis reveals that despite the many molecular differences between these species, the biofilm architecture differences can be described by only two control parameters: cellular aspect ratio and cell density. Further experiments using single-species mutants for which the cell aspect ratio and the cell density are systematically varied, and mechanistic simulations, show that tuning these two control parameters reproduces biofilm architectures of different species. Altogether, our results show that early-stage biofilm architecture is determined by mechanical cell-cell interactions which are conserved across different species and, therefore, provide a unifying understanding of biofilm architecture development.