Metabolic engineering of Pseudomonas taiwanensis VLB120 as chassis for the production of chorismate-derived bulk and fine chemicals

Increasing depletion of fossil resources requires a shift of industry towards a more sustainable production. This led to a focus on bio-based production of both bulk and fine chemicals.
Due to the robustness of Pseudomonas taiwanensis VBL120 as well as its highly versatile metabolism, this bacterium displays a suitable candidate for the production of a broad spectrum of compounds, especially aromatics. Chorismate is a key precursor for many aromatics, and we therefore modified P. taiwanensis to increase chorismate availability in the cell. This was achieved by targeting the bifunctional enzyme pheA, which catalyzes the first two steps from chorismate to the aromatic amino acids phenylalanine and tyrosine. Overall, metabolic engineering approaches could be applied to increase productivity up to 20.3±0.1% (Cmol/Cmol) from glucose and up to 25.4±2.1% (Cmol/Cmol) from glycerol, depending on the respective aromatic compound.
To demonstrate its applicability, production of different chorismate-derived hydroxybenzoates was shown. These compounds can serve either as plastic building blocks, food additives, or as precursor for more complex secondary metabolites. In the latter context, we enabled the conversion of 2,3-dihydroxybenzoate (DHB) into myxochelin. In this metal-chelating siderophore, two DHB molecules are coupled via a lysine molecule. Like many other non-ribosomal peptides, native myxochelin biosynthesis results in low titers with hosts that are difficult to handle. Transfer of its synthesis to P. taiwanensis enables more efficient metabolic engineering, while also opening up process engineering options like supplementation of different carbon sources or addition of a second phase extractant.