Separation and partial purification of biosurfactants by foam fractionation technique

Abstract

Pseudomonas aeruginosa SP4, isolated from petroleum-contaminated soil in Thailand, was used to produce a biosurfactant from nutrient broth supplemented with palm oil. Normally, crude biosurfactant has been extracted from culture broth by organic solvent extraction. Owing to high cost and toxicity to environment and human health of organic solvents, foam fractionation, a surfactant-based separation, was used in this study to concentrate and remove the biosurfactant from cell-free nutrient broth solution. The effects of the air flow rate, column height, pore size of sinter glass disk, solution volume and the collecting time on enrichment ratio and percentage of biosurfactant recovery were investigated to determine the optimum condition for separating the biosurfactant from nutrient broth solution. It was found that increasing of either column height or pore size of sinter glass disk resulted in higher enrichment ratio but lower percentage of biosurfactant recovery. On a contrary, increasing of air flow rate resulted in a decrease in enrichment ratio but an increase in the percentage of biosurfactant recovery. The initial biosurfactant solution and biosurfactant in collapsed foam from foam fractionation process were fractionated by using HPLC-ELSD technique. The HPLC patterns of both biosurfactant samples are identical. However, the peak intensities of the biosurfactant in the collapsed foam were higher than those of the initial biosurfactant solution, indicating the higher biosurfactant concentration.