Micro-aerobic production of isobutanol with Pseudomonas putida and investigation of its resilience to substrate limitations

Abstract

The transition from an economy based on fossil resources to a regenerative economy is imminent yet uncertain. Despite an awareness of the scarcity of fossil fuels and the increasing natural disasters due to climate change, the world’s renewable energy supply still constitutes less than 20% of the total energy supply. To reduce humankind’s carbon footprint, next-generation biofuels, such as ethanol or isobutanol, have the potential to revolutionize the transportation energy demand. These biofuels can be produced from renewable feedstock in large bioreactors using microorganisms. However, inhomogeneities, such as carbon or oxygen gradients in large-scale bioreactors, often limit the efficiency of such industrial bioprocesses. The soil bacterium Pseudomonas putida has the potential to supersede existing industrial workhorses like Escherichia coli or Corynebacterium glutamicum due to its natural tolerance towards alcohols, its versatile repertoire of stress responses, and its affinity to a broad range of substrates. This thesis aims to investigate the capability of isobutanol production in P. putida KT2440 and to explore its performance during large-scale stress.