Regulating Bacterial Behavior within Hydrogels of Tunable Viscoelasticity

Area of Science:

• Biomaterials Engineering
• Synthetic Biology
• Microbiology

Background:

• Engineered living materials (ELMs) integrate living organisms into synthetic matrices.
• Controlling cellular behavior within 3D environments is key for ELM design and application.
• Understanding spatial confinement effects on embedded microorganisms is crucial for material function and impact.

Purpose of the Study:

• To investigate how 3D hydrogel matrix properties influence bacterial growth and metabolic activity.
• To determine the role of mechanical properties, specifically stiffness and crosslinking, in regulating bacterial behavior within ELMs.
• To explore the potential for matrix design to control the composition and function of microbial ELMs.

Main Methods:

• Utilized a Pluronic-based hydrogel network with tunable mechanical properties via acrylate crosslinking.
• Incorporated bacteria at low density within the hydrogel matrix.
• Quantified bacterial colony size, sphericity, and protein production as a function of matrix crosslinking degree and stiffness.

Main Results:

• Bacterial colony size was inversely correlated with the degree of permanent crosslinks, indicating size control by matrix stiffness.
• Increased matrix stiffness led to decreased colony volumes and increased sphericity.
• Protein production yields peaked in hydrogels with intermediate permanent crosslinking degrees.

Conclusions:

• Hydrogel matrix design, particularly its mechanical properties, can effectively regulate the behavior of embedded microorganisms in ELMs.
• Spatial confinement within the hydrogel matrix influences bacterial growth, morphology, and function.
• The findings suggest parallels between matrix design for microbial ELMs and 3D mammalian cell culture, highlighting broad applicability.