At a foam fractionation column height of 30 cm, lipopeptiderecovery increased from 8 to 57% when aeration rate increased from 50 to 200 mL/min, but enrichment ratios varied from 1.4 to 2.0(Fig. 6). Thus, foam fractionation column height was increased from30 to 60 cm in order to provide higher retention time of the sepa-rated foam in the column, which enhanced the drainage of culturemedium back into medium storage. It was found that the enrich-ment ratio increased to 3.2 at the foam fractionation column heightof 60 cm and aeration rate of 300 mL/min; whereas, lipopeptiderecovery showed a little reduction to 54%. When increasing aerationrate to 400 mL/min, a high reduction in both enrichment ratio andrecovery was found. HPLC profile of lipopeptide extracted from thefoamate had less impurity peaks than that from the culture medium(Fig. 7a and b). Thus, the foam fractionation process was able toincrease the product purity. The chromatogram of crude lipopep-tides showed peaks with retention times similar to the standardsurfactin (98% pure) from Sigma-Aldrich at 11.02, 14.88, and16.36 min (Fig. 7c). Davis et al. [36] also applied foam fractionationtechnique to separate lipopeptide from culture medium of Bacillussubtilis ATCC 21332. They found that a mean surfactin enrichmentof 2.9 was reached in the cell-free process compared to 1.7 for thecell-containing system and the surfactin recovery for the cell-freeand cell-containing process were similar, 97 and 97%, respectively.