Development of a self-regulating microbial system for the production of recombinant proteins from renewable raw material

The looming fact that fossil raw material will be depleted one day has brought much attention to renewable materials in recent years. Lignocellulose, being the most abundantly available renewable raw material on the planet, might play an important role in the future. It is the structural framework of woody plant cell walls and consists mainly of lignin, hemicellulose, and cellulose. After being subjected to suitable pre‑treatments the main product is a mixture of different carbohydrates.

The aim of this research project is to use these sugars as completely as possible in a microbial system. This research was a joint project of the University of Ulm and the University of Hohenheim. The Department of Bioprocess Engineering (University of Hohenheim) has vast experience in the field of microbial bio‑production with a focus on process development and optimization. The Rosenau group of the Centre of Quantum Biological Science (University of Ulm) is active in the field of biological chemistry and pharmaceutical biotechnology. They focus on biomaterials and have expertise in developing peptide and protein-based active ingredients.

For this research project the bacteria Pseudomonas putida KT2440 was chosen. Metabolic engineering was used to modify wild type bacteria into strains that are specialized to metabolize certain sugars. Subsequently, the most efficient strains were selected by cultivation experiments and evaluation of typical biotechnological efficiency parameters. The chosen strains were further engineered to produce human serum albumin and bovine αs1‑casein as reference proteins and evaluated as potential production hosts in a subsequent step. In the last phase of the project, the system was tested under real conditions in a bioreactor with different lignocellulose-hydrolysates as substrates.