Sophorolipid production by Candida bombicola on oils with a special fatty acid composition and their consequences on cell viability

Laboratory of Industrial Microbiology and Biocatalysis, Department of Biochemical and Microbial Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
Biotechnology Letters (Impact Factor: 1.59). 10/2010; 32(10):1509-14. DOI: 10.1007/s10529-010-0323-8
Source: PubMed


Sophorolipids production by the yeast Candia bombicola is most favourable when glucose is used as a carbon source in combination with a hydrophobic carbon source such as a common vegetable oil. Most vegetable oils are comprised of C16-C18 fatty acids, an ideal range for sophorolipid production. The use of oils with either shorter or longer fatty acids, such has coconut oil or meadowfoam oil, respectively, was evaluated. Such oils did not contribute to enhanced sophorolipid production when compared to cultures run on glucose as the sole carbon source. Moreover, a toxic effect of medium-chain fatty acids towards stationary C. bombicola cells was demonstrated.

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    • "This is best represented by cultivation of the yeast in absence of any hydrophobic carbon source such that sophorolipid synthesis occurs merely de novo from glucose. In this case, about 20% of the sophorolipids contain a C16:0 lipid tail, while 46 and 34% contain a C18:1 and C18:0 fatty acid tail, respectively (Van Bogaert et al. 2010). The fatty acid composition is on the one hand governed by the specificity of the cytochrome P450 monooxygeanse CYP52M1, converting the common fatty acid to a terminal or subterminal hydroxylated one. "
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    ABSTRACT: Altering glycolipid structure by genetic engineering of S. bombicola is a recently started research topic and worthy alternative to the unsuccessful selective feeding strategies conventionally applied to reach this goal. One question to be addressed when expressing heterologous proteins in S. bombicola is the activity of the subsequent biosynthetic enzymes towards such modified substrates. In this scope, we studied the substrate specificity of the UDP-glucosyltransferases UgtA1 and UgtB1, responsible for the stepwise synthesis of sophorolipids from a hydroxylated fatty acid, and that of the acetyltransferase, responsible for acetylation of the sophorolipid molecule. All enzymes showed specificity towards a C18:1 chained acceptor and both glucosyltransferases were highly selective towards the UDP-glucose donor. Severe product inhibition of the glucosyltransferases explains the limited accumulation of sophorolipid intermediates by earlier created single deletion mutants of S. bombicola. Finally, a more detailed study of the acetylation of sophorolipid intermediates sheds light on the enzymatic cascade during synthesis. © FEMS 2015. All rights reserved. For permissions, please e-mail:
    Full-text · Article · Aug 2015 · FEMS Yeast Research
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    ABSTRACT: 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.
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    ABSTRACT: High-performance liquid chromatography (HPLC) with evaporative light scattering detection (ELSD) and HPLC with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) methods were implemented and optimized to separate and identify sophorolipids (SLs) produced by Rhodotorula bogoriensis and Starmerella bombicola. SLs are carbohydrate-based amphiphilic biosurfactants with increased interest in pharmaceutical and environmental areas. Rhodotorula bogoriensis and Starmerella bombicola are mainly producers of respectively C22, and C16 and C18 SLs. Mass fragmentation patterns of SLs produced by both yeasts were investigated by HPLC-ESI-MS/MS in the positive mode for [M+Na]+. Based on the established fragmentation pattern, SLs produced by both yeasts were identified and characterized. A correlation between HPLC-ELSD and HPLC- ESI-MS/MS methods was established and made possible the identification of SLs by the HPLC-ELSD technique. TLC is a common tool for the analysis of SLs mixtures. In this work, TLC scrapped bands were analysed by HPLC-ELSD and HPLC-MS allowing the correlation between R(F) values and the identification of sophorolipids by this technique. Identification of monoacetylated and diacetylated C24:0 hydroxy fatty acids sophorolipids produced by Rhodotorula bogoriensis was for the first time accomplished with this study. Although present in lower quantity these longer chain SLs can assume special importance regarding their biological activity and surface active properties.
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