Bubbling insights: unveiling the true sophorolipid biosynthetic pathway by Starmerella bombicola
Abstract Background The yeast Starmerella bombicola is renowned for its highly efficient sophorolipid production, reaching titers and productivities of (over) 200 g/L and 2 g/(L h), respectively. This inherent efficiency has led to the commercialization of sophorolipids. While the sophorolipid biosy...
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BMC
2024-08-01
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| Series: | Biotechnology for Biofuels and Bioproducts |
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| Online Access: | https://doi.org/10.1186/s13068-024-02557-7 |
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| author | Sophie L. K. W. Roelants Stijn Bovijn Elvira Bytyqi Nicolas de Fooz Goedele Luyten Martijn Castelein Thibo Van de Craen Zhoujian Diao Karolien Maes Tom Delmulle Maarten De Mol Sofie L. De Maeseneire Bart Devreese Wim K. Soetaert |
| author_facet | Sophie L. K. W. Roelants Stijn Bovijn Elvira Bytyqi Nicolas de Fooz Goedele Luyten Martijn Castelein Thibo Van de Craen Zhoujian Diao Karolien Maes Tom Delmulle Maarten De Mol Sofie L. De Maeseneire Bart Devreese Wim K. Soetaert |
| author_sort | Sophie L. K. W. Roelants |
| collection | DOAJ |
| description | Abstract Background The yeast Starmerella bombicola is renowned for its highly efficient sophorolipid production, reaching titers and productivities of (over) 200 g/L and 2 g/(L h), respectively. This inherent efficiency has led to the commercialization of sophorolipids. While the sophorolipid biosynthetic pathway has been elucidated a few years ago, in this study, it is revisited and true key intermediates are revealed. Results Recently, Starmerella bombicola strains developed and evaluated in the past were reevaluated unveiling unexpected findings. The AT enzyme encoded in the sophorolipid biosynthetic gene cluster is the only described enzyme known to acetylate sophorolipids, while the SBLE enzyme encoded by the SBLE gene is described to catalyze the conversion of (acetylated) acidic sophorolipids into lactonic sophorolipids. A double knockout of both genes was described to result in the generation of bolaform sophorolipids. However, new experiments performed with respective S. bombicola strains Δsble, Δat Δsble, and ∆at revealed inconsistencies with the current understanding of the SL pathway. It was observed that the ∆sble strain produces mainly bolaform sophorolipids with higher acetylation degrees instead of acidic sophorolipids. Furthermore, the ∆at strain produces predominantly bolaform sophorolipids and lactonic sophorolipids with lower acetylation degrees, while the ∆at ∆sble strain predominantly produces bolaform sophorolipids with lower acetylation degrees. These results indicate that the AT enzyme is not the only enzyme responsible for acetylation of sophorolipids, while the SBLE enzyme performs an intramolecular transesterification reaction on bolaform glycolipids instead of an esterification reaction on acidic sophorolipids. These findings, together with recent in vitro data, led us to revise the sophorolipid biosynthetic pathway. Conclusions Bolaform sophorolipids instead of acidic sophorolipids are the key intermediates in the biosynthetic pathway towards lactonic sophorolipids. Bolaform sophorolipids are found in very small amounts in extracellular S. bombicola wild type broths as they are very efficiently converted into lactonic sophorolipids, while acidic sophorolipids build up as they cannot be converted. Furthermore, acetylation of sophorolipids is not exclusively performed by the AT enzyme encoded in the sophorolipid biosynthetic gene cluster and acetylation of bolaform sophorolipids promotes their transesterification. These findings led to the revision of the industrially relevant sophorolipid biosynthetic pathway. |
| format | Article |
| id | doaj-art-fa09f4012050464d9002b797b56be560 |
| institution | Kabale University |
| issn | 2731-3654 |
| language | English |
| publishDate | 2024-08-01 |
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| series | Biotechnology for Biofuels and Bioproducts |
| spelling | doaj-art-fa09f4012050464d9002b797b56be5602025-01-19T12:13:43ZengBMCBiotechnology for Biofuels and Bioproducts2731-36542024-08-0117111110.1186/s13068-024-02557-7Bubbling insights: unveiling the true sophorolipid biosynthetic pathway by Starmerella bombicolaSophie L. K. W. Roelants0Stijn Bovijn1Elvira Bytyqi2Nicolas de Fooz3Goedele Luyten4Martijn Castelein5Thibo Van de Craen6Zhoujian Diao7Karolien Maes8Tom Delmulle9Maarten De Mol10Sofie L. De Maeseneire11Bart Devreese12Wim K. Soetaert13Centre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent UniversityCentre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent UniversityCentre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent UniversityCentre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent UniversityCentre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent UniversityCentre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent UniversityCentre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent UniversityLaboratory of Microbiology—Protein Research Unit, Department of Biochemistry and Microbiology, Faculty of Science, Ghent UniversityR&D Department, Bio Base Europe Pilot Plant (BBEPP)Centre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent UniversityCentre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent UniversityCentre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent UniversityLaboratory of Microbiology—Protein Research Unit, Department of Biochemistry and Microbiology, Faculty of Science, Ghent UniversityCentre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent UniversityAbstract Background The yeast Starmerella bombicola is renowned for its highly efficient sophorolipid production, reaching titers and productivities of (over) 200 g/L and 2 g/(L h), respectively. This inherent efficiency has led to the commercialization of sophorolipids. While the sophorolipid biosynthetic pathway has been elucidated a few years ago, in this study, it is revisited and true key intermediates are revealed. Results Recently, Starmerella bombicola strains developed and evaluated in the past were reevaluated unveiling unexpected findings. The AT enzyme encoded in the sophorolipid biosynthetic gene cluster is the only described enzyme known to acetylate sophorolipids, while the SBLE enzyme encoded by the SBLE gene is described to catalyze the conversion of (acetylated) acidic sophorolipids into lactonic sophorolipids. A double knockout of both genes was described to result in the generation of bolaform sophorolipids. However, new experiments performed with respective S. bombicola strains Δsble, Δat Δsble, and ∆at revealed inconsistencies with the current understanding of the SL pathway. It was observed that the ∆sble strain produces mainly bolaform sophorolipids with higher acetylation degrees instead of acidic sophorolipids. Furthermore, the ∆at strain produces predominantly bolaform sophorolipids and lactonic sophorolipids with lower acetylation degrees, while the ∆at ∆sble strain predominantly produces bolaform sophorolipids with lower acetylation degrees. These results indicate that the AT enzyme is not the only enzyme responsible for acetylation of sophorolipids, while the SBLE enzyme performs an intramolecular transesterification reaction on bolaform glycolipids instead of an esterification reaction on acidic sophorolipids. These findings, together with recent in vitro data, led us to revise the sophorolipid biosynthetic pathway. Conclusions Bolaform sophorolipids instead of acidic sophorolipids are the key intermediates in the biosynthetic pathway towards lactonic sophorolipids. Bolaform sophorolipids are found in very small amounts in extracellular S. bombicola wild type broths as they are very efficiently converted into lactonic sophorolipids, while acidic sophorolipids build up as they cannot be converted. Furthermore, acetylation of sophorolipids is not exclusively performed by the AT enzyme encoded in the sophorolipid biosynthetic gene cluster and acetylation of bolaform sophorolipids promotes their transesterification. These findings led to the revision of the industrially relevant sophorolipid biosynthetic pathway.https://doi.org/10.1186/s13068-024-02557-7Starmerella bombicola lactone esteraseBiosurfactantsGlycolipidsBolaform sophorolipidsLactonic sophorolipids |
| spellingShingle | Sophie L. K. W. Roelants Stijn Bovijn Elvira Bytyqi Nicolas de Fooz Goedele Luyten Martijn Castelein Thibo Van de Craen Zhoujian Diao Karolien Maes Tom Delmulle Maarten De Mol Sofie L. De Maeseneire Bart Devreese Wim K. Soetaert Bubbling insights: unveiling the true sophorolipid biosynthetic pathway by Starmerella bombicola Biotechnology for Biofuels and Bioproducts Starmerella bombicola lactone esterase Biosurfactants Glycolipids Bolaform sophorolipids Lactonic sophorolipids |
| title | Bubbling insights: unveiling the true sophorolipid biosynthetic pathway by Starmerella bombicola |
| title_full | Bubbling insights: unveiling the true sophorolipid biosynthetic pathway by Starmerella bombicola |
| title_fullStr | Bubbling insights: unveiling the true sophorolipid biosynthetic pathway by Starmerella bombicola |
| title_full_unstemmed | Bubbling insights: unveiling the true sophorolipid biosynthetic pathway by Starmerella bombicola |
| title_short | Bubbling insights: unveiling the true sophorolipid biosynthetic pathway by Starmerella bombicola |
| title_sort | bubbling insights unveiling the true sophorolipid biosynthetic pathway by starmerella bombicola |
| topic | Starmerella bombicola lactone esterase Biosurfactants Glycolipids Bolaform sophorolipids Lactonic sophorolipids |
| url | https://doi.org/10.1186/s13068-024-02557-7 |
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