Developing a cloud point extraction process for lipopeptide recovery from cell-free broth of Bacillus sp. GY19

Abstract

ABSTRACT Biosurfactants can be potentially used in food, cosmetics, pharmaceuticals, and environmental remediation because of their biodegradability and low toxicity. However, it is very challenging to recover biosurfactants from fermented broth as they are temperature-sensitive and present at dilute concentrations. This study aims to develop an alternative process that uses cloud point extraction (CPE) to recover lipopeptides biosurfactant from cell-free broth of Bacillus sp. GY19. The nonionic surfactant, Triton X-100, was selected as the aqueous-based solvent for CPE. Under the optimal conditions lipopeptides concentration in Triton X-100 was 23,000 mg/L, which is 14.8-folds higher than that in cell-free broth. Lipopeptides and Triton X-100 exerted a positive synergistic effect in reducing the critical micelle concentration of mixed micelles with a β value of −1.9. This could be considered a co-benefit of using CPE for biosurfactant recovery. Two techniques for back extraction of lipopeptides after the CPE process were proposed. Silica gel 60 selectively adsorbed Triton X-100 with 44% removal, while maintaining lipopeptides recovery at 86%. Cold acetone precipitation could remove 99% of Triton X-100 by precipitating lipopeptides. However, a 1%(w/v) SDS solution had to be used to re-solubilize the dehydrated lipopeptide