Vegetable oil enhances sophorolipid production by Rhodotorula bogoriensis

The yeast Rhodotorula bogorensis produces sophorolipids of different structures to those produced by Candida bombicola. However, the yield is very low. To improve sophorolipid production by R. bogoriensis, vegetable oil was supplemented to the medium as a hydrophobic substrate: with rapeseed oil the sophorolipid yield was 1.26 g/l but without oil was 0.33 g/l. Cultures with meadowfoam oil produced 0.77 g sophorolipids/l. Lipase-treated meadowfoam oil, however, gave no significant increase in sophorolipid production. Possible explanations for the enhanced sophorolipid synthesis are discussed.