Biosurfactant Based Reverse Micellar Extraction of Lactoperoxidase from Whey: Exploitation of Rhamnolipid Characteristics for Back Extraction

ABSTRACT

Biosurfactant-based reverse micellar extraction of Lactoperoxidase (LP) was studied using Rhamnolipid (RL) as a biosurfactant. Different solvents were considered to select a suitable organic phase for forming reverse micelles (RM) to varying concentrations of RL for the extraction of LP from its synthetic aqueous solution. The effect of addition of nonionic surfactant as lipophilic linker, whey pH, and ionic strength of the whey was studied to improve the forward extraction of LP from acid whey. About 96.65% LP was extracted to the RM phase during forward extraction. Further, a new back extraction strategy was developed by harnessing the biosurfactant properties. The pH-specific protonation–deprotonation characteristic of the RL headgroups was exploited to overcome the back extraction of LP, which is the rate-limiting step. The back extraction in citrate buffer at pH 5 using 0.75 M KCl resulted in 85.71% active LP recovery with 8.4-fold purification. The effect of the extraction process on the antimicrobial activity of LP was further examined with S. aureus, and the multiplication of the organism was almost arrested even after 24 hr at 9°C.

KEYWORDS:

• Rhamnolipid
• whey protein
• bioseparation
• antimicrobial
• purification

Acknowledgments

The authors acknowledge the kind contribution of Dan Derr, Logos Technologies, and Nattaporn Lohitharn, and Stepan Company, for their timely support with Rhamnolipid samples and related technical data.

Disclosure statement

No potential conflict of interest was reported by the authors.

Novelty/Highlights

• Implementation of rhamnolipid-based reverse micelle system

• pH-specific protonation–deprotonation characteristic of rhamnolipid was exploited

• The back extraction was improved by modifying the ionic properties of rhamnolipid

• Achieved an active LP recovery of 85.71% with an 8.4-fold purification

• The back extracted LP showed better antimicrobial activities