Revealing Previously Unseen Channel Structures in Pseudomonas aeruginosa Biofilms with Multi-scale Imaging

Biofilms are complex microbial communities with increased antimicrobial resistance (AMR), posing significant challenges in both clinical and industrial settings. Naturally, biofilms are often polymicrobial, and monoculture studies fail to capture the interactions that occur in these environments. Previous research identified intra-colony channels in Escherichia coli mature colony biofilms, facilitating nutrient transport from the surrounding environment. This study utilised advanced multi-scale imaging techniques, including Confocal Laser Scanning Microscopy (CLSM) for high-resolution, three-dimensional reconstructions of biofilm structures, and mesoscopy with the Mesolens, for capturing differences in macrostructure across entire specimens at subcellular resolution.
Here, we have applied these advanced imaging methods to explore the internal architecture of a different but nonetheless biomedically important biofilm-forming pathogen, Pseudomonas aeruginosa. P. aeruginosa is, like E. coli, a rod-shaped Gram-negative bacterium, categorised by the World Health Organisation as a high-priority pathogen due to its increasing carbapenem resistance, reflecting its substantial impact in healthcare settings. Given that biofilms in clinical environments are rarely composed of a single species, we also investigated the structures in co-cultured E. coli/P. aeruginosa biofilms. Understanding the complexity and form of P. aeruginosa in single species biofilms and within co-cultured bacterial communities will inform better disease management and will assist in the development of new antimicrobial agents.