Influence of microorganism and plant oils on the structure of mannosylerythritol lipid (MEL) biosurfactants revealed by a novel thin layer chromatography mass spectrometry method
Mannosylerythritol lipids (MEL) are microbial glycolipid biosurfactants with great potential for application in cosmetics and household detergents. In current biotechnological processes, they are produced by basidiomycetous fungi, the Ustilaginaceae, as a complex mixture of different chemical structures. It was the aim of this paper to study the influence of producer organisms and substrates on the resulting MEL structures with a novel high-resolution HPTLC–MALDI-TOF method. Given the seven different microbes and four plant oils, our analysis revealed that the product concentrations varied strongly between organisms, while they were similar for the different substrates. Coconut oil presented an exception, since only one organism was able to synthesize MEL from this substrate in considerable yields. Analysis by GC-FID further showed that the chain length pattern of hydrophobic fatty acid side-chains was very specific for individual organisms, while substrates had only a minor influence on the chain length. Our novel HPTLC–MALDI-TOF combination method finally demonstrated the presence of multiple MEL sub-variants with differing acetylation and fatty acid chain lengths. It also revealed the production of a more hydrophilic biosurfactant mannosylmannitol lipid (MML) as a side-product in certain fungi. Overall, it was concluded that the pattern of produced biosurfactant structures are mainly governed by producer organisms rather than substrates.
KeywordsUstilaginaceae Fungi Structural analysis HPTLC–MALDI-TOF–MS GC-FID Mannosylmannitol lipids
We kindly thank Ulrike Götz, Felix Derwenskus and Renate Preisner from the Fraunhofer IGB for their assistance with gas chromatographic measurements.
This work by Alexander Beck was supported by a grant from the Ministry of Science, Research and the Arts of Baden-Württemberg (7533-10-5-85B) as part of the BBW ForWerts Graduate Program.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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