Recovery of purified lactonic sophorolipids by spontaneous crystallization during the fermentation of sugarcane molasses with Candida albicans O-13-1

Numerous studies have focused on how to obtain high yield of sophorolipids using low-cost materials as substrates, and there has been various work on the experimental methods for purifying lactonic sophorolipids. These studies have not yet obtained satisfied results in combining a low-cost fermentation process and the purification of lactonic sophorolipids. This study establishes a fed-batch fermentation process of purifying sophorolipids from Candida albicans O-13-1 using low-cost sugarcane molasses as the substrate. In the optimized conditions of this research, using sugarcane molasses as a substrate and product synthesis based on the temperature stage-controlled fermentation, our result indicates that sophorolipids production could reach 108.7 g/L. More importantly, lactonic sophorolipids can crystallize and precipitate during our established fermentation process. The structures and content of sophorolipids separated from the fermentation broth and sophorolipids crystallized in the fermentation broth were analyzed by a scanning electron microscope (SEM) and liquid chromatography–mass spectrometry (LC–MS). The fermentation process produced 90.5 g/L crystallized lactonic sophorolipids with 90.51% purity. This is an energy-saving and low-cost method to obtain such pure lactonic sophorolipids.