Pseudomonas biofilms spread more pyocyanin in lung tissue than on lab material

Chemical mapping found deeper pyocyanin presence in mouse lung explants than in biofilms grown on a synthetic surface.

Editorial illustration — not from the study.

Researchers grew Pseudomonas aeruginosa biofilms on polydimethylsiloxane, a synthetic material used as a laboratory model for biomedical devices, and on pieces of healthy mouse lung. They used matrix-assisted laser desorption/ionization mass spectrometry imaging to map molecules across the biofilms and surrounding tissue without adding labels.

Both models showed a broadly conserved set of molecules involved in bacterial communication, biofilm structure and metabolism. The lung-explant biofilms differed in the distribution of phenazines, especially pyocyanin, which was more prominent and penetrated deeply into the lung tissue.

What the imaging showed

The imaging method mapped several molecular families within the biofilms, including quorum-sensing molecules, phenazines and rhamnolipids. The overall molecular profile was conserved between the synthetic-surface and lung-explant models, but their spatial patterns differed. In particular, biofilms formed on lung explants showed increased pyocyanin production, with pyocyanin spreading into the lung tissue. The study also optimized sample preparation, embedding materials and sectioning approaches to preserve biofilm structure and tissue integrity during imaging.

Why the lung model matters

The findings show that the surrounding material can shape the chemical organization of a Pseudomonas biofilm. A lung environment produced a stronger, more tissue-invasive pyocyanin pattern than the laboratory surface, highlighting why biofilms studied on synthetic materials may not fully represent their behavior in infected tissue. Mapping these molecules in place could help researchers examine how bacterial metabolism and host tissues interact during chronic infections.

Evidence and caveats

This was an experimental study using mass spectrometry imaging in two laboratory models: biofilms on polydimethylsiloxane and ex vivo pieces of healthy mouse lung. The lung model used Pseudomonas aeruginosa PAO1-eGFP, while the synthetic-surface experiments also included PA14, and the biofilms were examined after 24 hours. The study maps molecular presence and distribution, but the excerpts do not report quantitative pyocyanin amounts or clinical outcomes. Because the work used a synthetic surface and short-term mouse lung explants rather than people with chronic lung infections, the findings cannot by themselves establish how the patterns occur in patients.

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