Biosurfactants – Production and Optimization

Today biosurfactants are defined mainly as chemically produced products from renewable resources. They are used as surfactants or emulsifiers in the textile industry, in household cleaners, and cosmetics. Despite their structural diversity, so far biosurfactants produced by microorganisms are only found in few products. As part of the project BioSurf the Fraunhofer IGB with its project partners is developing surfactants from microorganisms as well as enzymatically produced surfactants based on renewable resources. The Fraunhofer IGB is focussing on optimizing smut fungi (Ustilago maydis, Pseudozyma ssp.) to produce the glycolipids cellobiose lipid and mannosylerythritol lipid. By process improvement and the corresponding product preparation, biosurfactants will be economically manufactured and thus will be able to compete with conventional surfactants.

Surfactants form an integral part of our everyday life with applications reaching far beyond our hygienic needs ranging from asphalt over food to fuel additives all the way to compounds with antibiotic activities. Currently, surfactants are produced on a scale of almost 14 million tons worldwide. A majority of surfactants is still manufactured from fossil resources. The project BioSurf aims at an increased replacement of petro-based surfactants by bio-based surfactants, which can be generated from renewable resources and are environmentally friendly. The focus hereby is on microbially and enzymatically produced biosurfactants.

Biosurfactants, the sustainable alternative

Many microorganisms naturally produce surface-active compounds, the biosurfactants, which encompass a broad spectrum of molecular diversity. These compounds include glycolipids, lipopeptides, lipoproteins and heteropolysaccharides, among others. The properties of these biosurfactants regarding performance, degradability and sustainability are often comparable to or even often outrange synthetic surfactants and are of interest for many different fields of application. Improved production and purification processes, effective production strains and a higher demand for “green” products have made several biosurfactants ready for the market in recent years. The best example is sophorolipids from Candida bombicola, which is currently produced by several companies as an additive for household cleaners and dishwashing agents.

Central topic of the BioSurf project is the identification of novel enzymes and microorganisms for new and more efficient biosurfactant production. The cellular regulatory processes involved in biosurfactant production are to be investigated and consequent metabolic engineering for the improvement of the respective microorganisms also with respect to stress resistance during production will be performed for the construction of new production strains of biosurfactants with better productivity. Furthermore, we will carry out enzyme design combining rational and or evolutionary methods for the enzymatic synthesis of surfactants with advantageous properties.

A crucial point in the project is the scale-up of bioprocesses including innovative downstream processing using membrane technologies and immobilized enzymes and in situ product removal from fermentations or biochemical conversions. By coupling of fermentation and separation technology we do not only expect to improve the downstream process, but also envisage the improvement of surfactant production by avoiding product inhibition conditions. These objectives will be achieved by connecting five technical work packages that address the entire biosurfactant value chain.

BioSurf is part of a series of projects that focus on biosurfactants. These are a focal point at the Fraunhofer IGB. Fundamental work has been possible by the support of a PhD stipend from DBU. Preliminary research on glycolipids (cellobiose lipids, mannosylerythritol lipids) has been done in the FNR funded project PolyTe. The EU-project O4S that was granted in 2012 is helping expand the application of biosurfactant as emulsifiers and in cosmetics. This is geared especially toward the production of biosurfactants using organically certifiable resources and processes.

Further information:

www.biosurf.fraunhofer.de
→ www.igb.fraunhofer.de/en/competences/molecular-biotechnology/white-biotechnology/biosurfactants.html

The production of two groups of glycolipids has already been successfully established at the Fraunhofer IGB. Mannosylerythritol lipids (MEL) have been produced with a yield of up to 100 g/L from P. aphidis and cellobiose lipids (CL) from U. maydis with a yield of up to 30 g/L. Furthermore, a number of related surfactants with different properties were produced by enzymatic or chemical modification of the preparation process. Their application potential is currently being characterized by the project partner Ecover. The preparation is being driven forward by the project partner VITO.

Further modification will be introduced by targeted metabolic engineering. For this purpose genome sequences of P. aphidis and U. maydis  were determined by parallel sequencing as part of BioSurf. In addition, a transcriptome of P. aphidis was produced by RNAseq under MEL-production conditions. By analyzing the data, the biosynthesis-cluster that is responsible for the MEL-production was identified in U. maydis in which they were already described. Furthermore, they were identified in P. aphidis as a new synthesis cluster with homologous genes to U. maydis. These data are now a template for targeted metabolic engineering.

The sequencing of the smut fungi P. aphidis and U. maydis will be very helpful for the analysis of a large number of smut fungi with diverse surfactant repertoires. BioSurf has already identified numerous MEL variants in various Pseudozyma spp. Seven other Pseudozyma spp were studied for this purpose. The MEL-product spectrum of these species differs with respect to the number and length of hydrophobic side chains. This can have significant effects on the surfactant properties.

  • Karlsruher Institut für Technologie KIT
  • c-LEcta GmbH
  • Flemish Institute for Technological Research (Belgium)
  • Tormans Engineering Noord BVBA (Belgium)
  • Ecover Belgium NV (Belgium)
  • LISBP (France)