Surfactants are molecules which lower the surface tension of liquids leading to an increased miscibility of different liquid phases (e.g., water and oil). This unique feature is exploited in a wide variety of applications, including household detergents, pharmaceuticals or cosmetics. Biosurfactants, including glycolipids like rhamnolipids (RL), can be produced via fermentation using renewable resources, e.g. sugars and/or plant oil, thus avoiding the use of crude oil.
RLs, as industrially established example of glycolipids, have been investigated within the FocusLab Bio². They are composed of up to two rhamnose moieties (hydrophilic part) and two β-hydroxyalkanoic acids (HAAs) with varying chain lengths between C8-C24 (hydrophobic part). This structural diversity of RLs is caused by the interplay of three enzymes: RhlA is responsible for the variance in the fatty-acid chain length. RhlB adds the first rhamnose molecule to the HAAs. The resulting mono-RL can be transformed to di-RL by RhlC adding a second rhamnose moiety.
Different congeners of RLs are expected to have different features; however, the relationship between the structural diversity of RLs and their physicochemical properties remains unclear. DesignR aims at filling this knowledge gap. Utilizing RLs as industrially established exemplary glycolipid, fundamental knowledge regarding structure-function relationships will be gathered. Findings will serve to lay the foundation for an even broader knowledge platform for production and purification of designer glycolipids with yet to be explored applications and market potentials. For this, structure-function relationships of different types of purified RLs and RL mixtures will be investigated in-depth. This will be addressed by (i) microbial production of mono- and di-RL, (ii) selective separation of mono-RL, di-RL, and HAAs, and (iii) bio- and physicochemical characterization of produced mixtures.
Since production of RLs is inevitably accompanied by varying levels of HAAs, separation of RLs and HAAs by normal-phase chromatography will be evaluated. This will aid in allocating the impact of specific congeners to the overall physicochemical properties (e.g. foaming and emulsification) of the mixture.
The development of bio-based and sustainable technologies and products constitutes a central part of the bioeconomy. This includes the replacement of still widely used synthetic compounds by adequate natural substances to be derived from biochemical pathways. Glycolipids, representing a class of biosurfactants, as bio-based alternatives to chemical surfactants with their numerous potential applications, are in the core of the bioeconomy strategy. The recent launch of RheanceOne®, a mixture of di-RLs and HAAs, by Evonik demonstrates the general economic feasibility of RL production processes and supports the potential of those substances in particular for the bioeconomy in NRW.
The topic addressed in DesignR is essential for the FocusLab Bio² as it provides additional in-depth information on the structure-function relationship of glycolipids, utilizing RLs as industrially established exemplary system. A major drawback of biosurfactants compared to traditional petrochemistry is their limited structural variability to match requirements for applications and at the same time their production as mixtures of congeners which hampers the replacement of oil based surfactants with biosurfactants1. However, the market potential of glycolipids or even specific glycolipid congeners is insufficiently studied. Furthermore, a lack of applications in which certain biosurfactants are clearly (economically) superior to petrol based surfactants hampers also the market penetration.
Bio2 delivered a wealth of innovative solutions for strain engineering, process monitoring, aeration, product recovery, and life cycle assessment aiming at an effective production process. In DesignR, attention is turned towards a scalable purification procedure to yield specific species out of the mixture obtained from a bioprocess. Separation of RLs and HAAs has not been realized in RheanceOne®. In addition, a production platform providing control of product properties and enabling a targeted design of new glycolipids with selected properties will open new applications in the future. Such purified/tailored compounds could complement the di-RL dominated RL/HAA mixture already commercialized by Evonik. Furthermore, the envisaged technologies to be developed in DesignR will provide tailored glycolipids for toxicity and application tests within the BioSC network. In a BioSC SeedFund project, rhamnolipids have been shown to facilitate resistance against the plant parasitic nematodes for plants. One crucial insight gained is that different rhamnolipid congeners feature different effectivities in providing resistance. Fundamental knowledge gathered within DesignR will serve as initialization of a competence platform for the future market of glycolipids. Here, the specific competences and expertise of the partners involved are extremely important for the FocusLab Bio² and the BioSC in general, because they represent core expertise regarding strain development, analytics, cultivation, and downstream processing of RLs. While Bio² has, in its ambition to develop a production process for RLs, focused on mono-RLs as target compounds, DesignR will now focus on the in-depth evaluation of the produced product spectrum.
The topic contributes to profiling of the BioSC as biosurfactants remain an important example for the transition from a crude-oil-based to a bio-based economy. DesignR aims to provide suitable strategies for purification and a platform to enable the production of novel glycolipid compositions based on renewable resources. Enhanced control of the product composition may also support their acceptance for consumers, who care about the origin of ingredients used in daily life. In addition, increased antimicrobial activity has been described for several secondary metabolite compounds developed in the FocusLab CombiCom when they were applied in combination with biosurfactants2. Hence, tailored RL and glycolipid mixtures may have additional potential for application of compounds already existing or to be developed by the putative CombiCom follow-up project “TaiLead”.
Dr. Holger Klose
Head of Research | Alternative Biomasss
Institute of Bio- and Geosciences - Plant Sciences
Forschungszentrum Jülich GmbH
phone: +49 2461 61334
Prof. Jaeger, Dr. Stephan Thies and Sonja Kubicki, Institute of Molecular Enzyme Technology (IMET), Heinrich Heine University Düsseldorf
Prof. Andreas Jupke and Andreas Biselli, Chair of Fluid Process Engineering (AVT.FVT), RWTH Aachen University
Prof. Jochen Büchs and Dr. Nina Ihling, AVT.BioVT, RWTH Aachen University
01.08.2020 - 31.07.2021
The total budget of DesignR is 119,108 €. DesignR is is part of the NRW-Strategieprojekt BioSC and thus funded by the Ministry of Culture and Science of the German State of North Rhine-Westphalia.