Broadening the applicability of biological surfactants
Surfactants (surface-active substances) lower surface tension. They are present in various aspects of our daily life, particularly in cleaning agents and cosmetics, where primarily non-renewable petrochemical resources are used for their manufacture. Replacement of the petrochemical derived surfactants by biological ones can significantly reduce the environmental impact (e.g. better biodegradable in waste-water, lower eco-toxity, use of renewable resources). Yet limitation in the types of naturally occurring biosurfactants impedes their more widespread use. The BIOSURFING (New-to-nature biosurfactants by metabolic engineering: Production and application) project was therefore established to improve the structural diversity of commercially available biosurfactants. Project partners engineered the yeast Starmerella bombicola, which is particularly good at producing glycolipid biosurfactants. The aim was to expand the range of useful glycolipids beyond the natural variety and create tailor-made glycolipids with new and better physical and chemical properties. Initially, four new strains of S. bombicola were investigated and developed. The modified yeasts' fermentation processes were subject to scale-up and some modifications introduced for an economical yet productive medium and fermentation parameters and to minimise foam production. As new-to-nature compounds have different properties to their natural counterparts, a new technique for product recovery and purification was developed for one particular strain and others adapted accordingly on the basis of tolerable levels of impurity production. Partners assessed samples and gave feedback, which prompted further modifications. The knowledge gained about the required purity and specifications was used to develop new methods for monitoring and removing contaminants, resulting in high-quality products. Several applications were explored, including general surfactant use, cosmetics and cleaning products. The researchers also looked at biological characteristics and behaviour at the nano- and mesomolecular scales, and explored the genomes, transcriptomes and proteomes of novel yeast strains and engineered more complex modifications. The ability of BIOSURFING to bioengineer glycolipid biosurfactant structure in a way currently possible only with petrol-based surfactants has the potential to revolutionise the surfactant market. Such advances will open the door to new applications and processes while significantly reducing environmental impact.
Keywords
Biosurfactants, BIOSURFING, metabolic engineering, Starmerella bombicola, glycolipids
