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From Niche to Bulk - Glycolipids and Derivatives Synthesized from Sugar

Authors: 
Germer, A., RWTH Aachen University

While rhamnolipids are discussed for decades as substitutes of oil-based molecules in such different applications as emulsifier in food or oil recovery, as foaming agent in shampoos, and surfactants in household detergents, very few applications exist in the market. Existing challenges are high production costs that arise besides other reasons from the use of plant oils as carbon source and the use of pathogenic bacteria as production host that immediately reduces application possibilities.

In this contribution we report on our rhamnolipid development platform with examples how we overcome the existing limitations. Using a GRAS organism as host1 (Pseudomonas putida KT2440) and sugars (glucose, xylose) as carbon sources opens new possibilities for rhamnolipid production. The constructed production strain reaches an at least 6-times improved carbon yield on substrate when compared to the existing fermentations with P. aeruginosa2. Notably, a driven by demand metabolic engineering approach was used that reduces the number of genetic interventions3. The new challenge of hyper-foam formation due to the absent plant-oil organic phase is converted into an in-situ product removal strategy that allows simple product purification4.

The developed technology enables the diversification of products by varying the number of rhamnose residues and the chain length of the OH-fatty acids. The different products (congeners) are quantified by a novel LC-MS technique5. Notably, while almost every publication on rhamnolipids or glycolipids in general starts with an argument on environmental friendliness and safe use, not much is reported on the latter, which we attended to change6. Without any rhamnosyltransferases, the engineered host produces OH-alkanoic acids (HAAs) at high rate, yield, and titer7. These HAAs compete besides other uses for bulk applications with neutral lipids from yeast and algae, however with the advantage of extracellular product accumulation. A novel application, the synthesis of 1,3-diols will be presented.

The results are discussed in the context of market needs for (glyco-)lipids.

References

  1. Wittgens A, Tiso T, Arndt TT, …, Wichmann R,…, Rosenau F, Blank LM: Growth independent rhamnolipid production from glucose using the non-pathogenic Pseudomonas putida KT2440. Microb Cell Fact 2011, 10
  2. Blank LM, Rosenau F, Wilhelm S, Wittgens A, Tiso T. (2013). Means and methods for rhamnolipid production, WO 2013/041670 A1
  3. Tiso T, Sabelhaus P, Behrens B, Hayen H, Blank LM. Creating metabolic demand as engineering strategy in Pseudomonas putida - Rhamnolipd synthesis as example. [submitted].
  4. Blank LM, Küpper B, del Amor Villa EM, Wichmann R, Nowacki C. (2013). Foam adsorption, WO 2013/087674 A1
  5. Behrens B, Engelen J, Tiso T, Blank LM, Hayen H. (2016). Characterization of rhamnolipids by liquid chromatography/mass spectrometry after solid-phase extraction. Anal Bioanal Chem [accepted].
  6. Johann S, Seiler TB, Tiso T, Bluhm K, Blank LM, Hollert H. (2016). Mechanism-specific and whole-organism ecotoxicity of mono-rhamnolipids. Sci Total Environ 548-549: 155-163.
  7. Blank LM, Tiso T, Germer A. (2015). Extracellular production of designer hydroxyalkanoyloxy alkanoic acids with recombinant bacteria, EP15175922