Mariana Itzel Velasco
The production of environmental friendly products has had a growing interest for the replacement of petrochemical products. For a successful transition, efficient cell factories are needed, which requires design-based metabolic engineered strains. Through the use of modified strains of E. coli we aim to achieve a more complete understanding of the interactions between metabolic and genetic networks.
Polyhydroxybutyrate is one of the most well-known and studied polyhydroxyalkanoates (PHAs), therefore will be taken as a model study for this research. The production of PHB in E. coli offers several advantages such as the purification of the polymer can be done easily and that can be controlled by metabolic engineering.
The metabolic pathways to produce PHB have already been introduced in E. coli, however their production is limited due to the nutrient starvation condition, and so far it has not been achieved a continuous production of PHB. Therefore the aim of our approach is to design a reprogrammable balance between growth and product formation under common growth conditions.
For the formation of PHB are required metabolic intermediates such as Acetyl CoA and NADPH, which are also important metabolites in the central metabolic pathways. Therefore the product and biomass formation may result in a competition for such metabolites. To obtain a balance between growth and product formation, we will study the regulatory interactions of the metabolic network with different strategies first controlling the growth rate using chemostat cultivations, and changing the nature of the carbon source.
The main objectives of the project are:
- To design a reprogrammable balance between growth and product formation under common growth conditions
- To identify metabolite-gene interactions by quantitative experiments and modelling
- To determine and study the roles of the signalling metabolites in the interaction between the metabolic and regulatory networks
- To direct the nature and availability of the nutrients, changing the net stoichiometry of glycolysis
- To develop a comprehensive model to describe the observed changes and to predict the outcome of similar metabolic interventions
These goals will be achieved in close collaboration with the research group Institute of Biomedical Sciences in Universidade de São Paulo (Brazil).
- Aldor, I. S., & Keasling, J. D. (2003). Process design for microbial plastic factories: metabolic engineering of polyhydroxyalkanoates. Current opinion in biotechnology, 14(5), 475-483.
- Carlson, R., Wlaschin, A., & Srienc, F. (2005). Kinetic studies and biochemical pathway analysis of anaerobic poly-(R)-3-hydroxybutyric acid synthesis in Escherichia coli. Applied and environmental microbiology, 71(2), 713-720.
- Lu, Jingnan, Tappel, Ryan C. and Nomura, Christopher T.(2009)'Mini-Review: Biosynthesis of Poly(hydroxyalkanoates)',Polymer Reviews,49:3,226 — 248
- Nicolas, C., Kiefer, P., Letisse, F., Krömer, J., Massou, S., Soucaille, P., ... & Portais, J. C. (2007). Response of the central metabolism of< i> Escherichia coli</i> to modified expression of the gene encoding the glucose-6-phosphate dehydrogenase. FEBS letters, 581(20), 3771-3776.
- Taymaz-Nikerel H, de Mey M, Ras C, ten Pierick A, Seifar, RM, van Dam JC, Heijnen JJ, Gulik WM van (2009) Development and application of a differential method for reliable metabolome analysis in Escherichia coli. Anal. Biochem.
- Tyo, K. E., Fischer, C. R., Simeon, F., & Stephanopoulos, G. (2010). Analysis of polyhydroxybutyrate flux limitations by systematic genetic and metabolic perturbations. Metabolic engineering, 12(3), 187-195