Synthetic biology tools to control growth and production in Escherichia coli
Abstract
Climate change is a growing concern worldwide. With the amount of energy and resources we use today, we would need 1.7 Earths to cover our consumption in a sustainable way. The main contributing factor to the changing climate is the extraction and use of fossil resources for production of fuels and chemicals. This releases high amounts of carbon dioxide to the atmosphere, which drives global warming. To minimize the environmental impact, it is critical that we find new, sustainable options to oil-based manufacturing. For centuries, humans have used microorganisms to make everything from beer and wine to bread, yogurt, cheese, and kimchi. In the recent decades, scientific breakthroughs within gene technology and DNA sequencing have enabled the use of microbes in novel applications. By rewiring microbial metabolism, we can establish cell factories that utilize renewable resources to sustainably produce many of the chemicals, fuels and materials that are currently made from fossil resources. However, most of these bioproducts are more expensive to produce than oil-derived products. In order to make cell factories economically feasible, it is important to find new ways to optimize the yield, titer and productivity of bioproduction processes. This thesis presents new tools and methods that can be used to increase product yields and control growth and production in the microbial cell factory Escherichia coli. A screening of the E. coli genome was carried out to identify genes and intergenic regions that, when inhibited, decouples growth and production. Identified targets that were shown to stop cell growth and increase production capacity were further used to improve production of a single-domain antibody. Using proteomics, it was found that the growth decoupling strains were metabolically active and did not exhibit a typical stationary phase response. Finally, an autoinducible gene expression system based on the tryptophan operon and the T7 RNA polymerase was developed and applied for production of a protein and a biochemical. The system relies on tryptophan depletion and does not require addition of expensive inducers.
Info
Thesis PhD, 2020
UN SDG Classification
DK Main Research Area
Science/Technology
