The use of fatty acid esters to enhance free acid sophorolipid synthesis

• Published in: Biotechnology letters Vol. 28; no. 4; pp. 253 - 260
• Main Authors: ASHBY, Richard D, SOLAIMAN, Daniel K. Y, FOGLIA, Thomas A
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01.02.2006; Springer Nature B.V
• Subjects: Alcohols - chemistry; Biological and medical sciences; Biotechnology; Candida - classification; Candida - metabolism; Candida bombicola; Cell Culture Techniques - methods; Culture Media - chemistry; Culture Media - metabolism; Esters; Ethanol; Fatty acids; Fatty Acids - chemistry; Fatty Acids - metabolism; Fermentation; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Ionization; Lipids - biosynthesis; Lipids - chemistry; Liquid chromatography; Mass spectrometry; Soybean Oil - chemistry; Species Specificity; Fungi; Candida bombicola; fatty acid esters; Yeast; Candida; sophorolipids; Fungi Imperfecti; Fatty acids; Mass spectrometry; Thallophyta
• ISSN: 0141-5492; 1573-6776
• DOI: 10.1007/s10529-005-5527-y

Fatty acid esters were prepared by transesterification of soy oil with methanol (methyl-soyate, Me-Soy), ethanol (ethyl-soyate, Et-Soy) and propanol (propyl-soyate, Pro-Soy) and used with glycerol as fermentation substrates to enhance production of free-acid sophorolipids (SLs). Fed-batch fermentations of Candida bombicola resulted in SL yields of 46 +/- 4 g/l, 42 +/- 7 g/l and 18 +/- 6 g/l from Me-Soy, Et-Soy, and Pro-Soy, respectively. Liquid chromatography with atmospheric pressure ionization mass spectrometry (LC/API-MS) showed that Me-Soy resulted in 71% open-chain SLs with 59% of those molecules remaining esterified at the carboxyl end of the fatty acids. Et-Soy and Pro-Soy resulted in 43% and 80% open-chain free-acid SLs, respectively (containing linoleic acid and oleic acid as the principal fatty acid species linked to the sophorose sugar at the omega-1 position), with no evidence of residual esterification.