Characterization of Patterned Microbial Growth Dynamics in Aqueous Two-Phase Polymer Scaffolds

Area of Science:

• Biotechnology
• Microbiology
• Biomaterials

Background:

• Microbial-mammalian co-culture in vitro presents challenges in maintaining distinct cellular environments.
• Aqueous two-phase systems (ATPS) offer a liquid scaffold for confining microbial growth.
• Polyethylene glycol (PEG) and dextran (DEX) form stable ATPS for biological applications.

Purpose of the Study:

• To characterize the stability of PEG/DEX ATPS under varying bacterial loading and biofilm maturation.
• To determine the effects of initial bacterial density and polymer concentration on ATPS containment.
• To investigate microbial growth impacts on ATPS interfacial properties.

Main Methods:

• Prepared two PEG/DEX ATPS formulations (5% and 10% w/v).
• Resuspended Escherichia coli at various optical densities (ODs) in the DEX phase.
• Monitored E. coli containment, growth dynamics, and ATPS stability over time.
• Assessed interfacial tension reduction using fluorescein isothiocyanate (FITC)-DEX and contact angle measurements.

Main Results:

• Lower initial bacterial seeding densities resulted in greater containment within the DEX phase.
• The 10% PEG/10% DEX formulation provided longer containment times for E. coli.
• Microbial growth, even below physical capacity, disrupted ATPS stability and reduced interfacial tension.
• ATPS stability was proportional to polymer concentration and inversely proportional to seeding density and culture time.

Conclusions:

• PEG/DEX ATPS can confine microbial growth, with stability influenced by polymer concentration and bacterial load.
• Microbial activity can alter ATPS properties, impacting containment and interfacial tension.
• These findings provide a basis for controlling microbial growth in heterotypic co-culture platforms.