Sophorolipid production from biomass hydrolysates.

Although extensive research has been conducted on producing sophorolipids using Candida (Starmerella) bombicola from pure sugars and various oil sources, production of this biosurfactant has not been evaluated when cells are cultivated in lignocellulosic hydrolysates. Here, we report for the first time that C. bombicola is capable of producing sophorolipids on hydrolysates derived from sweet sorghum bagasse and corn fiber. Without oil supplementation, a sophorolipid concentration of 3.6 and 1.0 g/L was detected from cultures with bagasse and corn fiber hydrolysates, respectively. With the addition of soybean oil at 100 g/L, the yield of sophorolipids from these two hydrolysates in the same order was 84.6 and 15.6 g/L. Surprisingly, C. bombicola consumed all monomeric sugars and nonsugar compounds in the hydrolysates, and cultures with bagasse hydrolysates had higher yield of sophorolipids than those from a standard medium which contained pure glucose at the same concentration.