Harting, ClaudiaTeleki, AttilaBraakmann, MariusJankowitsch, FrankTakors, Ralf2024-08-012024-08-0120241751-79151751-79151897924518http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-ds-147675http://elib.uni-stuttgart.de/handle/11682/14767http://dx.doi.org/10.18419/opus-14748l-Methionine (l-Met) has gained remarkable interest due to its multifaceted and versatile applications in the fields of nutrition, pharmaceuticals and clinical practice. In this study, the fluxes of the challenging l-Met biosynthesis in the producer strain Escherichia coli (E. coli) DM2853 were fine-tuned to enable improved l-Met production. The potential bottlenecks identified in sulfur assimilation and l-Met synthesis downstream of O-succinyl-l-homoserine (OSHS) were addressed by overexpressing glutaredoxin 1 (grxA), thiosulfate sulfurtransferase (pspE) and O-succinylhomoserine lyase (metB). Although deemed as a straightforward target for improving glucose-to-Met conversion, the yields remained at approximately 12%-13% (g/g). Instead, intracellular l-Met pools increased by up to four-fold with accelerated kinetics. Overexpression of the Met exporter ygaZH may serve as a proper valve for releasing the rising internal Met pressure. Interestingly, the export kinetics revealed maximum saturated export rates already at low growth rates. This scenario is particularly advantageous for large-scale fermentation when product formation is ideally uncoupled from biomass formation to achieve maximum performance within the technical limits of large-scale bioreactors.eninfo:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by/4.0/660article2024-04-25