UNRAVELING BIOFILM ASSEMBLY: HOW MATRIX COMPONENTS GOVERN EMERGENT MECHANICAL PROPERTIES

Bacteria self-produce and self-organize an extracellular matrix (ECM) forming a biofilm that enhances their chances for survival against harsh environmental conditions through their adaptation to such scenarios. Moreover, they are of great interest for their potential to be genetically engineered for biomaterial purposes.

The ECM is mainly composed of exopolysaccharides, amyloid proteins and eDNA. While the interactions between amyloid fibers and exopolysaccharides have been shown to be determining for biofilm architecture and mechanical properties, the exact nature of these interactions remains elusive in the complex biofilm context. Alongside, the contribution of these polymers, specifically amyloids, on how the ECM adapts to different environments have not been studied in detail. In general, it is not clear at what length scale bacterial ECM interactions occur, what are the contributions of water in these interactions, nor what are tehir implications on biofilm emergent properties.

In this work, we developed a multi-scale, and interdisciplinary platform to study not only the intreaction between exopolysaccharides and amyloids in the ECM, but also to further understand the role amyloid fibers play in increasing the bacteria survivance under different environomental cues. We evaluated E. coli microscopic features using cryo-FIBSEM and confocal microscopy, and evaluated their mechanic properties through nano-indentation experiments. Using spectroscopy, electronic microscopy, and other biophysical techniques we characterize the ECM components and their chemical stability.

The results revealed the biophysical features of the ECM components is ratio dependent where the formed composite contributes to the biofilm water adsorption, and mechanical properties. We also showed that under different environmental conditions, the bacteria tune the amyloid structure contributing to the mechanical properties of the biofilm formed. This knowledge on microbial ECM assembly opens new avenues for engineering living materials, especially for the use of bacterial biofilms as a source of bio-sourced materials, and for new designs on strategies to erradicate biofilms.

This work was supported by Max Plank Society.