Castor oil as secondary carbon source for production of sophorolipids using Starmerella bombicola NRRL Y-17069.

Abstract

Sophorolipids (SLs), a prominent member of the biosurfactants family are produced in acidic and/or lactonic form by yeast Starmerella bombicola NRRL Y-17069 when grown on hydrophilic or hydrophobic or both carbon sources. In current study, ricinoleic acid rich castor oil (10%) was used as hydrophobic and glycerol (10%) was used as hydrophilic carbon source. The yields of 24.5 ± 0.25 g/l sophorolipids were analyzed by anthrone and HPLC method which further increased upto 40.24 ± 0.76 g/l sophorolipids using fed batch process at 5L fermenter level. The structures of sophorolipids synthesized on castor oil were elucidated by liquid chromatography-mass spectrometer (LC-MS), (13)C and (1)H NMR. The results indicated that the ricinoleic acid (RA) gets hydroxylated at ω-1 position but incorporated into sophorolipids through already available hydroxyl group at 12(th) position. It resulted in the production of a novel sophorolipids with hydroxyl fatty acid as side chain and has applications as surfactant for novel drug delivery, anti microbial agent, cosmetic ingredient and emulsifier.