Industrial saponins

The aim of this project is to bring saponin production into the domain of industrial biotechnology to make this diverse group of biosurfactants available for commercial exploitation at the required scale, structure specificity & cost, in the first instance for home & personal care (HPC) use. We have already demonstrated that saponins can synergise with conventional surfactants to reduce the total surfactant level required for cleaning performance in laundry detergents, and that such mixtures are particularly effective at low temperatures. Saponins are plant-derived triterpenoidal or steroidal surfactants. Saponins currently have limited commercial availability, being sourced from natural plant materials. This supply is deficient in scale, is of limited structure specificity and is too expensive for Unilever's intended use in laundry detergents. Unilever's concentrated detergents business alone would require 100 tonnes pa of saponin at 0.1% level and 20% product range penetration. Leading saponin supplier Desert King produces only 20 tonnes active saponin pa from natural extracts. Furthermore, we have demonstrated that certain saponin structures are significantly more effective than others. The current sources of saponins are natural extracts and comprise a heterogeneous mixture of saponin structures. Our IB innovation will enable considerable enrichment for the most effective saponin structures. Current commercial saponins are too expensive at $35/kg for crude extracts for use in anything other than premium products. We expect IB to be a more cost effective route to saponin supply.

In a current project (TSB 131168), we have demonstrated production of tailored saponins in Nicotiana benthamiana and have expanded the synthetic biology tool kit genes and enzymes for tailored saponin bioengineering. However, this tobacco platform is not sufficiently scalable for commercial production. We need to transfer the saponin synthetic pathways into a microbial platform. We have selected yeast, Saccharomyces cerevisiae, as the most appropriate platform. Our aims are to push science and technology boundaries in multiple dimensions: (1) to transfer saponin metabolic pathways from model plant platform to yeast and engineer the pathway for commercially viable yield; although an academic proof of concept of simple monoglycosylated saponin production in yeast exists, further innovation is required to enable complex hyperglycosylated saponin production and to tackle yield & flux optimisation; (2) for downstream process development and scale up; (3) to further develop the triterpene toolbox of enzymes, genes and pathways for specific saponin structure enrichment & production; (4) to further understand the solution microstructure and surface adsorbed layer properties of mixtures of saponin & conventional surfactants, and (5) to continue to develop tangible benefits and structure-function relationships demonstrated in TSB 131168 for inclusion of saponins in model HPC formulations, extending the complexity of the models to include associated detergent technologies such as enzymes & dispersants. The above innovations will collectively enable a powerful business case for saponin commercialisation to be constructed.

As described in proposal submitted to IUK.