One of the main bottlenecks in continuous bioprocesses is the stability of the biocatalyst. Therefore, long-term industrial applications are rare. This project focuses on biofilms as new designer biocatalysts, with the final goal of large-scale applications in fine chemical bioprocesses. So far, the industrial use of biofilms was mainly restricted to wastewater treatment and off-gas cleaning. However, their beneficial aspects of self-immobilization, increased tolerance against toxic substrates and products, and the possibility to reach high cell-densities are our motivation to employ biofilms also for biotransformations and think of new biofilm reactor concepts.
1. Stress response in biofilms (MERCUR project, see details below) (Babu Halan)
2. Debottlenecking Pseudomonas sp. strain VLB120 for iso-butanol production (Karsten Lang)
3. Modulation of the EPS matrix in Pseudomonas sp. strain VLB120∆C biofilms (Karolin Schmutzler)
4. Segmented flow biofilm reactors and its applications (Rohan Karande)
Stress response in biofilms
Universität Duisburg-Essen / Biofilm Centre - Molecular Enzyme Technology and Biochemistry (MEB) and Aquatic Microbiology: Prof. Bettina Siebers, Prof. Hans-Curt Flemming, Dr. Jost Wingender, Silke Jachlewski, Jens Benninghoff
The goal of this project is to understand the response of archaeal and bacterial biofilms towards process related conditions relevant for the biotechnical production of chemical compounds. Biofilms as new designer biocatalysts offer the advantages of enhanced tolerance to environmental stress factors and long-term stability, allowing for the conversion of biologically challenging compounds and continuous processes. Two model organisms are investigated: the mesophilic bacterium Pseudomonas sp. strain VLB120 (TU Dortmund) and the archaeon Sulfolobus acidocaldarius (Universität Duisburg-Essen). Main focus is on the influence of solvents involved in biotransformation processes, which are most often toxic to the biocatalyst, impairing process performance especially of planktonic cultures. When exposed to such solvents, the intrinsic response of the cells in the biofilms is multifaceted (Figure 1).
Upon exposure to environmental stress, bacteria are known to enter into a viable but non-culturable (VBNC) state. An important aspect will be to investigate the influence of solvent stress on the vitality and physiological activity of biofilms and the possible induction of the VBNC state of the biofilm cells. The objective is to identify and optimize the conditions for the use of biofilms in solvent-dependent biotechnical applications.
To analyze solvent exposed biofilms, we focus on non-invasive, time-resolved and on-line methodologies based on confocal laser scanning microscopy and flow cell cultivation systems. In addition, biochemical assays (e.g. Lowry assay, phenol-sulfuric acid method) for the analysis of whole biofilms and their extracellular polymeric substances (EPS) as important structural and functional components of the biofilm matrix substances are widely applied in this study.
This project is financed by Mercator Research Center Ruhr (Mercur) which primarily motivates the research cooperation among the regional universities.
|Figure 1: Conceptual theme of the project.|