Purification of a Novel Lipopeptide Biosurfactant By Green Recovery Methods

FA-Glu is a novel biosurfactant that is produced by a genetically-modified strain of Bacillus subtilis on glucose-mineral salts media. It has unique properties compared to other biosurfactants and petroleum-based surfactants that make it suitable for several applications. In particular, its reduced toxicity to fish, low critical micelle concentration and high  dispersant-to-oil ratio FA-Glu  make it an attractive candidate for use in oil spill remediation.

Economic production of biosurfactants will improve their acceptability and augment their use, as well as reduce the need for synthetic surfactants. One approach for reducing production costs is through fermentation of low-cost feedstocks (preferably agricultural co-products) coupled with the use of efficient “green” recovery methods. Examples include membrane filtration and foam fractionation.

In this study, purification of FA-Glu from fermentation broth by froth floatation and ultrafiltration was explored. The effects of air flow rate, foam height and initial volume of the fermentation broth on enrichment and purification were tested. Additionally, membranes with different MWCO's were tested to optimize purification of FA-Glu from fermentation broth. Chemical analyses of product streams were used to identify processing parameters to maximize biosurfactant yields and purities. Purification strategies that may enhance the purity are presented.