On the production and identification of medium-chained sophorolipids

Sophorolipids are biologically produced surfactants that consist of a hydrophilic sophorose moiety bound to a hydroxylated lipophilic substrate. The highest levels of production are currently achieved using Candida bombicola ATCC 22214, an ascomycotous yeast, as the production organism. The lipophilic moiety is typically found to have a length between C(16) and C(18) and thus the applications of readily produced sophorolipids with regard to cleaning purposes are somewhat limited. Experiments were performed to evaluate the conditions under which a beta-oxidation deficient strain of C. bombicola is able to convert 1-dodecanol into sophorolipids. Both shakeflask and bioreactor cultures yielded C(12), or medium-chained, sophorolipids and the effect of aeration on the production level was investigated and found to favour limited aeration. Analysis of the conversion products was performed through RP-HPLC and the formation of new-to-nature sophorolipids was confirmed by MS. The use of the beta-oxidation deficient strain under limited aeration yielded at least 15 g/L of medium-chained sophorolipids, which is more than in the wild-type strain or when employing full aeration.