Enhanced fermentation of biosurfactant mannosylerythritol lipids on the pilot scale under efficient foam control with addition of soybean oil

Biosurfactant mannosylerythritol lipids (MELs) are green alternatives to chemically synthesized surfactants. However, these biosurfactants typically have a high cost-of-production limiting their adoption for industrial applications. In this study, an optimized fermentation process at pilot scale to furnish MELs with Pseudozyma aphidis DSM 70725 was developed. This involved the optimization of the levels of Fe2+, Fe3+ to improve the fermentation efficacy and the use of soybean oil to reduce the foam generated during fermentative production of MELs. The MELs titer, production rate and the conversion ratio of the carbon source was enhanced to 61 g/L, 0.255 g/L/h and 0.68 g/g, respectively. These optimizations resulted in approximately 100% improvement over regular fermentation processes and are amenable to the large-scale fermentation of MELs employing soybean oil as an antifoam agent to overcome foaming issues.