The Rosenau Lab

Rhamnolipids are biosurfactants with an enormous potential to replace or complement classic surfactants in industrial applications. They consist of one or two L-rhamnose residues linked to one or two 3-hydroxyfatty acids of various chain lengths, which can also contain unsaturated carbon-carbon bonds, yielding a wide variety of different structures each with its specific physico-chemical properties. Since different applications of surfactants require specific tenside characteristics related to surface tension reduction, emulsification, and foaming etc., rhamnolipids represent a platform molecule which harbors an enormous potential to adopt tailor-made properties to meet a huge variety of demands of surfactants for food-, healthcare-, and biotechnological applications. We develop novel technologies to synthesize tailor-made rhamnolipids based on the biotechnological use of different enzymes responsible for rhamnolipid biosynthesis originating from different naturally rhamnolipid-producing microorganism. Furthermore, we aim on future strategies to determine the number of L-rhamnose and 3-hydroxyfatty acids as well as their specific chain lengths and unsaturations to produce customized rhamnolipids perfectly tuned for every application.
The use of still unusual carbon sources (e. g. sugars and sugar mixtures from lignocellulose) fort he production of bioproucts is a current research topic).
Projects have are and have been funded by „Fachagentur Nachwachsende Rohstoffe“, „Deutsche Bundesstiftung Umwelt“ and „Forschungsprogramm Bioökonomie Baden-Württemberg“ (https://biooekonomie-bw.uni-hohenheim.de/startseite).

The rhamnolipid project has received the „Forschungspreis NRW - Zukunft erfinden 2014“ in the category „transfer“ and was nominated in the category „Lifesciences“) (https://www.pressebox.de/inaktiv/provendis-gmbh/Roter-Teppich-fuer-NRW-Erfindungen-PROvendis-laedt-zur-Preisverleihung-des-HochschulWettbewerbs-ZukunftErfindenNRW/boxid/675190

(further reading: Wittgens A, Rosenau F. „On the road towards tailor-made rhamnolipids: current state and perspectives“. Appl Microbiol Biotechnol. 2018;102(19):8175-8185. doi: 10.1007/s00253-018-9240-x. Review. PubMed PMID: 30032436)

 

Cell culture (published in Scientific Reports)
Hydrogels are recognized as promising materials for cell culture applications due to their ability to provide highly hydrated cell environments. The field of 3D templates is rising due to the potential resemblance of those materials to the natural extracellular matrix. Protein-based hydrogels are particularly promising because they can easily be functionalized and can achieve defined structures with adjustable physicochemical properties. We have developped systems based on the use of recombinant lectin B, a sugar-binding protein with four binding cavities, to enable reversible cell integration into a macroporous protein hydrogel matrix. By functionalizing hydrogel precursors with saccharose, lectin B can both bind to sugar moieties on the cellular surface as well as to the modified hydrogel network. Cells could be grown in this matrix and could be eluted (harvested) in perfectly viable state within minutes by addition of L-fucose to the cell-loaded hydrogels to make cells available for further use.
(further reading: Bodenberger N, Kubiczek D, Trösch L, Gawanbacht A, Wilhelm S, Tielker D, Rosenau F. Lectin-mediated reversible immobilization of human cells into a glycosylated macroporous protein hydrogel as a cell culture matrix. Sci Rep. 2017 ;7(1):6151. doi: 10.1038/s41598-017-06240-w. PubMed PMID: 28733655; PubMed Central PMCID: PMC5522389)

„Smart“ antiinfective materials  
A similar system has been developped with the intention to remove pathogens from infected wounds and was published in Biomacromolecules. Infections with multiresistant pathogens are a leading cause for mortality worldwide. Just recently, the World Health Organization (WHO) increased the threat rating for multiresistant Pseudomonas aeruginosa to the highest possible level. With this background, it is crucial to develop novel materials and procedures in the fight against multiresistant pathogens. In this study, we present a novel antimicrobial material, which could find applications as a wound dressing or antimicrobial coating. Lectins are multivalent sugar-binding proteins, which can be found in a variety of plants and bacteria, where they are associated with biofilm formation. By immobilizing lectin B on a protein-based hydrogel surface, we provided the hydrogel with the ability to immobilize ("catch") pathogens upon contact. Furthermore, another hydrogel layer was added which inhibits biofilm formation and releases a highly potent antimicrobial peptide to eradicate microorganisms ("kill"). The composite hydrogel showed a high antimicrobial activity against the reference strain Pseudomonas aeruginosa PAO1 as well as against a carbapenem-resistant clinical isolate (multiresistant Gram-negative class 4) and may thus represent a novel material to develop a new type of antimicrobial wound dressings to prevent infections with this problematic pathogen of burn or other large wounds. (see:

Bodenberger N, Kubiczek D, Halbgebauer D, Rimola V, Wiese S, Mayer D, Rodriguez Alfonso AA, Ständker L, Stenger S, Rosenau F. Lectin-FunctionalizedComposite Hydrogels for "Capture-and-Killing" of Carbapenem-Resistant Pseudomonas aeruginosa. Biomacromolecules. 2018 19(7):2472-2482. doi:10.1021/acs.biomac.8b00089. Epub 2018 Apr 25. PubMed PMID: 29665678.