Novel Organic Solvent Nanofiltration Approaches for Microbial Biosurfactants Downstream Processing

Area of Science:

• Biotechnology and Bioprocessing
• Separation Science
• Microbial Product Recovery

Background:

• Glycolipid biosurfactants, including mannosylerythritol lipids (MELs), are crucial microbial products often produced at high titers but low purity.
• Current purification methods for MELs rely on organic solvents, leading to poor solvent recyclability and increased costs due to contaminants like triacylglycerols and free fatty acids.

Purpose of the Study:

• To develop and evaluate an innovative downstream purification method for MELs.
• To improve MEL purity while minimizing product loss and enabling solvent recycling.
• To assess the efficacy of organic solvent nanofiltration (OSN) and different membranes for MEL purification.

Main Methods:

• A two-stage purification process involving initial triacylglycerol separation followed by OSN for removing other lipid derivatives.
• Evaluation of commercial (GMT-oNF-2, PuraMEm-600, DuramMem-500) and homemade polybenzimidazole (PBI) membranes via diafiltration.
• Assessment of methanol and ethyl acetate as solvents, and activated carbon for decoloration.

Main Results:

• A PBI 26% membrane achieved 87-90% MEL purity with 14.7-15.3% product loss using two diavolumes (DV) of methanol or ethyl acetate.
• A two-sequential cascade filtration using the GMT-oNF membrane yielded MELs with 98% purity and 11.6% product loss.
• Decoloration was successfully achieved using activated carbon.

Conclusions:

• The developed OSN-based downstream process offers a unique, cost-effective solution for purifying microbial biosurfactants like MELs with minimal product loss.
• The method facilitates solvent recycling, contributing to greener and more economical bioprocesses.
• Achieved high purities (up to 98%) are suitable for reagent-grade applications.