Establishing biotechnological processes within the envisaged circular bioeconomy requires the integration of all stages of process development. In this context, a joint operational window for the microbial production and in situ extraction of rhamnolipids in a novel multiphase loop reactor was defined. While outcomes of this thesis are related to the presented system, interdisciplinary approaches can be transferred to other bioprocesses, advocating the transition to a sustainable bioeconomy.

A transition from a fossil-based to a sustainable bio-based industry is crucial due to environmental pollution. This can be achieved by the production of chemicals with microbes using renewable substrates. In this context, the promising host P. putida KT2440 was engineered for efficient utilization of lignocellulose-derived substrates and heterologous production of biosurfactants, namely rhamnolipids. Thereby, the thesis contributes to establishing eco-friendly processes.

Biotechnological applications become a forward-looking alternative to chemical production of fine and bulk chemicals. Microbial hosts with beneficial properties are used to produce all required products. Synthetic biology is tailoring the generation of whole-cell catalysts by metabolic and genetic engineering. Therefore, reliable and well-characterized tools are necessary. This thesis contributes to P. putida KT2440 synthetic biology and is increasing the number of characterized tools.

In this study, a recombinant non-pathogenic Pseudomonas putida KT2440 was applied for rhamnolipid or 3-(3-hydroxyalkanoyloxy)alkanoic acid production. The production and recovery of these surfactants was intensified by the integration of foam fractionation and desorption techniques into the bioreactor cultivation process. Furthermore, the accumulation of bacteria at the gas-liquid interface of the foam could be diminished by deleting genes encoding hydrophobic cell-surface structures.

Liver cirrhosis is accompanied by a variety of severe complications that drastically reduce patients' life expectancy. The aim of this study was to improve therapeutical interventions for liver cirrhosis patients by identifying patients with a high need for treatment and by characterizing the pathophysiological changes in cirrhosis patients to facilitate drug development and pharmacotherapy.A hallmark of disease progression in liver cirrhosis is the transition from a compensated to a decompensated state. While patients are mostly asymptomatic in the compensated state, the decompensated stage...

Reduced compounds can be produced using metabolically engineered microbes, often relying on redox-cofactor-dependent biocatalysis. The prerequisite for outstanding performance requires a basic understanding of the redox metabolism of the production host, a simple redox chassis, and a target molecule for which a metabolic pathway exists. This thesis addresses these prerequisites using the obligate aerobe Pseudomonas taiwanensis VLB120.The essentiality of the three NADH dehydrogenases of the respiratory chain of P. taiwanensis VLB120 was investigated. A mutant lacking all three NADH...

Climate change is a pressing global issue that is caused by the consumption of fossil fuels, which releases greenhouse gases into the atmosphere. Cell factories are biological systems that are engineered to produce a wide range of products, such as biofuels, bioplastics, and pharmaceuticals which can play a crucial part in reducing the dependency on fossil fuels. Additionally, cell factories can be made more efficient and sustainable by using advanced technologies such as metabolic engineering and synthetic biology. This thesis aimed to expand the genetic toolbox of Pseudomonas taiwanensis...

The sensation of "smell", caused by volatile organic compounds, is native to all domains of life. The sum of all emitted molecules is called the volatilome but the exploration of microbial volatiles is a sparsely populated research field. Saccharomyces cerevisiae is a common host for modern biotechnology and has been used for the biotechnological production of ethanol for most of human civilisation, but still, the gas phase above fermentations is yet to be fully understood. This work aims to contribute to the knowledge of different aspects of the yeast volatilome: avoiding unwanted volatiles,...