Metabolic engineering of Corynebacterium glutamicum for production of L-lysine from mannitol and mannitol-rich seaweed extracts

• Main Author: Hoffmann, Sarah Lisa
• Other Authors: Wittmann, Christoph
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Saarländische Universitäts- und Landesbibliothek 2020
• Subjects: ddc:570; Antarc*; Antarctica
• Online Access: http://nbn-resolving.org/urn:nbn:de:bsz:291--ds-331598; https://doi.org/10.22028/D291-33159

Nowadays, C. glutamicum belongs to the most important industrial microbes, especially in the production of L-lysine, which is mainly applied as feed supplement in animal nutrition. L-Lysine is currently fermented from agricultural crops such as corn and sugar cane. Especially from a sustainability perspective, it is necessary to find non-food raw materials for production. In this regard, seaweed as 3rd generation renewable is highly promising. In a first round of metabolic engineering, the glucose-based L-lysine producing strain LYS-12 served as starting point to extend the substrate spectrum to mannitol, the most abundant seaweed carbohydrate, by deleting the constitutively expressed mannitol repressor MtlR/AtlR. However, only small amounts of L-lysine were produced by this mutant, designated SEA-1. To further upgrade this basic strain, several rounds of systems metabolic engineering were applied. These aimed at improving the NADPH supply and recycling excess NADH, originating from catabolic mannitol oxidation and posing inhibitory effects on the cell. The finally constructed L-lysine producer C. glutamicum SEA-7 revealed superior production performance and achieved a L-lysine titer of 76 g L-1 from mannitol in a fed-batch process. Finally, SEA-7 was implemented into a cascaded value chain towards maximal sustainability using seaweed extracts from Laminaria digitata and Durvillaea antarctica, yielding 0.29 mol mol-1 and 0.41 mol mol-1 of L-lysine, respectively. Heutzutage gehört das Bakterium C. glutamicum zu den wichtigsten industriellen Produzenten, insbesondere zur Herstellung von L-Lysin, welches vor allem Anwendung in der Futtermittelindustrie findet. L-Lysin wird derzeit hauptsächlich aus Nutzpflanzen wie Mais oder Zuckerrohr hergestellt. Insbesondere vor dem Hintergrund der Nachhaltigkeit ist die Erschließung alternativer Rohstoffe unumgänglich. Meeresalgen stellen diesbezüglich als 3. Generation nachwachsender Rohstoffe eine vielversprechende Ressource dar. Mittels Metabolic Engineering wurde das ...