S74: Production of sophorolipids from soy molasses and bioglycerol

A heightened environmental awareness and geopolitical concerns have intensified the drive to develop biobased substitutes for fossil fuel-derived industrial chemicals. Microbial glycolipids such as sophorolipid (produced by Candida bombicola yeast) and rhamnolipid (produced by Pseudomonas sp.) are secondary metabolites suited for use as biobased substitutes of the petroleum-derived detergents; these glycolipids have a high surface-activity and also possess antimicrobial property. High production costs, however, are hampering the commercialization efforts of biosurfactants. We have explored the use of inexpensive industrial byproducts such as soy molasses and crude glycerol (i.e., a byproduct of biodiesel production) as fermentation substrates to help contain the production cost of sophorolipids. This paper reviews our work showing that soy molasses could support low-cost sophorolipids production by eliminating the use of higher cost yeast extracts (a nitrogen source) and glucose (a carbon source). We also showed that crude glycerol could serve as inexpensive carbon source for sophorolipids production. Moreover, the residual fatty acids in the crude glycerol unexpectedly provide a means to produce the low-foaming, free-acid form of the sophorolipids useful for certain applications. In an effort to manipulate the biosynthesis of sophorolipid, we have also cloned, functionally verified, and expressed in a heterologous host a glycosyltransferase gene from Candida bombicola. Our research yielded results that are valuable for future development of an economical production system of sophorolipid and its variants.