Knocking out the MFE-2 gene of Candida bombicola leads to improved medium-chain sophorolipid production |
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Authors: | Inge NA Van Bogaert Julia Sabirova Dirk Develter Wim Soetaert & Erick J Vandamme |
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Institution: | Laboratory of Industrial Microbiology and Biocatalysis, Department of Biochemical and Microbial Technology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium;and;Ecover Belgium NV, Malle, Belgium |
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Abstract: | The nonpathogenic yeast Candida bombicola synthesizes sophorolipids. These biosurfactants are composed of the disaccharide sophorose linked to a long-chain hydroxy fatty acid and have potential applications in the food, pharmaceutical, cosmetic and cleaning industries. In order to expand the range of application, a shift of the fatty acid moiety towards medium-chain lengths would be recommendable. However, the synthesis of medium-chain sophorolipids by C. bombicola is a challenging objective. First of all, these sophorolipids can only be obtained by fermentations on unconventional carbon sources, which often have a toxic effect on the cells. Furthermore, medium-chain substrates are partially metabolized in the β-oxidation pathway. In order to redirect unconventional substrates towards sophorolipid synthesis, the β-oxidation pathway was blocked on the genome level by knocking out the multifunctional enzyme type 2 (MFE-2) gene. The total gene sequence of the C. bombicola MFE-2 (6033 bp) was cloned (GenBank accession number EU371724 ), and the obtained nucleotide sequence was used to construct a knock-out cassette. Several knock-out mutants with the correct geno- and phenotype were evaluated in a fermentation on 1-dodecanol. All mutants showed a 1.7–2.9 times higher production of sophorolipids, indicating that in those strains the substrate is redirected towards the sophorolipid synthesis. |
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Keywords: | sophorolipids MFE-2 Candida bombicola biosurfactants yeast β-oxidation |
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