Beyond Amino Acids - Systems Metabolic Engineering of Corynebacterium Glutamicum for Materials and Health Care Products

For now almost six decades, Corynebacterium glutamicum has established as major industrial producer for l-amino acids, especially l-lysine [1, 2]. Systems biology and systems-level engineering substantially broadened the product spectrum, and leveraged the integration of C. glutamicum into the rising era of biorefinery application. Today, its product spectrum has the potential to serve consumer markets for health, nutrition, textiles, housing, energy, and agriculture [2]. In this work, we developed genetically defined producer strains of C. glutamicum for aspartate-derived products being applicable as materials and health-care products.

The production of diaminopentane – a valuable monomer building block for polyamide production – was realized on basis of the lysine-hyperproducer C. glutamicum LYS-12 [1]. Extending the terminal pathway by optimized expression of lysine decarboxylase [3], combined with elimination of by-product formation [4] and transport engineering [5] bred the streamlined C. glutamicum DAP-16 strain that produced diaminopentane with a high yield of 0.5 mol mol^-1, a final titer of 88 g L^-1, and a productivity of 2.2 g L^-1 h^-1 during fed-batch fermentation [6]. Diaminopentane was then purified to 99% purity by solvent extraction and distillation. Subsequent polymerization with sebacic acid from castor oil produced the 100 % bio-based polyamide PA5.10 exhibiting excellent material properties for industrial application [6]. Production of the chemical chaperon and cosmetic ingredient ectoine recruited a heterologous pathway from Pseudomonas stutzeri. Genome-based integration into one of the two lysine-biosynthetic branches enabled ectoine formation with simultaneous down-regulation of carbon flux towards lysine. Full elimination of lysine secretion and implementation of a fed-batch strategy elevated production up to a molar yield of 30 % whereby one of the highest reported ectoine productivities of 6.7 g L^-1 d^-1 was achieved [7]. Beyond, basic producers for metabolically related products are currently constructed as proof-of-concepts, awaiting further engineering towards attractive titers and yields.

[1] Becker J, Zelder O, Haefner S, Schroeder H, Wittmann C: From zero to hero – design-based systems metabolic engineering of Corynebacterium glutamicum for L-lysine production. ME 2011, 13:159.

[2] Becker J, Wittmann C. 2015. Advanced Biotechnology: Metabolically Engineered Cells for the Bio-Based Production of Chemicals and Fuels, Materials, and Health-Care Products. AngewandteChemie 54:3328.

[3] Kind S, Jeong WK, Schröder H, Wittmann C. 2010. Systems-wide metabolic pathway engineering in Corynebacterium glutamicum for bio-based production of diaminopentane. ME 12(4):341

[4] Kind S, Jeong WK, Schröder H, Zelder O, Wittmann C. 2010. Identification and elimination of the competing N-acetyldiaminopentane pathway for improved production of diaminopentane by Corynebacterium glutamicum. AEM 76(15):5175.

[5] Kind S, Kreye S, Wittmann C. 2011. Metabolic engineering of cellular transport for overproduction of the platform chemical 1,5-diaminopentane in Corynebacterium glutamicum. ME 13(5):617

[6] Kind S, Neubauer S, Becker J, Yamamoto M, Völkert M, Abendroth GV, Zelder O, Wittmann C. 2014. From zero to hero - Production of bio-based nylon from renewable resources using engineered Corynebacterium glutamicum. ME 25:113

[7] Becker J, Schäfer R, Kohlstedt M, Harder BJ, Borchert NS, Stöveken N, Bremer E, Wittmann C. 2013. Systems metabolic engineering of Corynebacterium glutamicum for production of the chemical chaperone ectoine. MCF 12:110