EAGER: Optical Coherence Elastography (OCE): A novel tool for rapid, non-destructive, spatially resolved quantification of mesoscale biofilm mechanical properties

Biofilms - microbial communities attached to surfaces - play critical roles in both engineered bioreactors and natural environments. Despite the importance of biofilm structure as an essential mediator of biofilm growth and activity, little is known about the relationship between biofilm structure and underlying mechanical properties that control retention of active biomass in biofilms. Further, there is a distinct lack of methods for co-registered nondestructive quantification of biofilm properties at the mesoscale (0.1-10 mm). To address this knowledge gap, the PIs propose to develop a novel methodology, termed Optical Coherence Elastography (OCE), for rapid quantitative 3D mapping of mesoscale viscoelastic mechanical properties in biofilms. Importantly, the approach is noninvasive and allows co-registered imaging of depth-resolved biofilm physical architecture, thereby enabling the relationship between mesoscale structural characteristics and mechanical properties to be probed. The project team will develop the OCE method and use it to assay properties and dynamics of mixed-culture biofilms representative of those employed for biological nitrogen (N) removal. Efforts will be organized around two specific objectives: Objective 1: Develop a dynamic OCE method for mesoscale nondestructive mapping of elastic moduli in environmental biofilms; and Objective 2: Employ OCE to quantify the relationship between mesoscale biofilm mechanical properties, morphology, and performance in mixed culture N-cycling biofilms. Initial applications of OCE will relate mesoscale gradients in Young's and Shear moduli to variation in biofilm roughness, internal porosity and thickness. Nondestructive elastography will enable time-series measurement of mesoscale structural and mechanical features during the development and maturation of these essential environmental biofilms.