Biofilms deform soft surfaces and disrupt epithelia

Area of Science:

• Microbiology
• Biophysics
• Biomaterials science

Background:

• Bacteria form biofilms, complex multicellular structures, during chronic infections and in the microbiota.
• Biofilm-host interactions are commonly assumed to be exclusively biochemical, overlooking mechanical contributions.
• The formation and mechanical impact of biofilms on soft, tissue-like materials are poorly understood.

Purpose of the Study:

• To investigate the mechanical forces exerted by bacterial biofilms on soft substrates.
• To elucidate the mechanisms by which biofilms deform materials and influence host physiology.
• To explore the role of mechanical stress in bacterial infection.

Main Methods:

• Utilized soft synthetic hydrogels as model substrates.
• Employed mechanical measurements and genetic mutations in matrix components.
• Combined biofilm formation studies with atomic force microscopy and cell culture assays.

Main Results:

• Pathogenic biofilms of *Vibrio cholerae* and *Pseudomonas aeruginosa* induced significant deformations in soft hydrogels.
• Biofilms generate internal mechanical stress through cell growth within the matrix, leading to buckling.
• Adhesion was identified as the mechanism for transmitting biofilm-induced forces to substrates.
• *V. cholerae* biofilms mechanically disrupted soft epithelial cell monolayers.

Conclusions:

• Biofilm formation involves significant mechanical processes that can deform host tissues.
• Mechanical forces, in addition to biochemical interactions, play a crucial role in biofilm pathogenesis.
• Biofilms represent a mechanical mode of infection with implications for disease progression and treatment.