Fractionation of Extracellular Polymeric Substances by Aqueous Three-Phase Partitioning Systems.

Area of Science:

• Biotechnology and Biopolymer Science
• Circular Economy Technologies
• Separation Science

Background:

• Extracellular polymeric substances (EPS) are crucial biopolymers for circular economy applications.
• Downstream processing of EPS presents significant challenges, hindering their wider industrial use.
• Existing separation methods often lack efficiency and scalability for complex biological mixtures.

Purpose of the Study:

• To investigate a three-phase partitioning (TPP) system as a novel fractionation technique for microbial EPS.
• To evaluate the impact of different phase-forming compounds and concentrations on EPS separation.
• To assess the recyclability of phase-forming compounds and the scalability of the TPP method for real EPS broths.

Main Methods:

• A three-phase partitioning (TPP) system was employed using various alcohol, polymer, and ionic liquid-based formulations with salt.
• The system was optimized for the separation of polysaccharide (EPS-PS) and protein (EPS-PN) components within EPS.
• Ultrafiltration (UF) and ultrafiltration/diafiltration (UF/DF) were used to assess recyclability and recovery of phase-forming compounds and fractionated EPS.

Main Results:

• The optimal TPP system (23 wt% ethanol and 25% K3C6H5O7) achieved 82% EPS-PS partitioning to the bottom phase and 76% EPS-PN recovery as a resolubilizable precipitate.
• Purity of EPS-PS and EPS-PN increased by 1.24-fold and 2.83-fold, respectively.
• High recovery yields (>99% for compounds, >80% for EPS) were achieved using UF/DF regeneration, demonstrating excellent recyclability and fractionation efficiency.

Conclusions:

• The TPP system, coupled with UF/DF, is a scalable, cost-effective, and efficient method for fractionating EPS from real microbial broths.
• This approach overcomes limitations observed when using model systems, highlighting its practical applicability.
• The study confirms the potential of TPP for advancing circular economy applications through improved biopolymer separation and recovery.