title: Cathodes enhance Corynebacterium glutamicum growth with nitrate and promote acetate and formate production.
abstract: The industrially important Corynebacterium glutamicum can only incompletely reduce nitrate into nitrite which then accumulates and inhibits growth. Herein we report that cathodes can resolve this problem and enhance glucose fermentation and growth by promoting nitrite reduction. Cell growth was inhibited at relatively high potentials but was significant when potentials were more reductive (-1.20V with anthraquinone-2-sulfonate as redox mediator or -1.25V vs. Ag/AgCl). Under these conditions, glucose was consumed up to 6 times faster and acetate was produced at up to 11 times higher yields (up to 1.1mol/mol-glucose). Acetate concentrations are the highest reported so far for C. glutamicum under anaerobic conditions, reaching values up to 5.3±0.3g/L. Herein we also demonstrate for the first time formate production (up to 3.4±0.3g/L) by C. glutamicum under strongly reducing conditions, and we attribute this to a possible mechanism of CO2 bioreduction that was electrochemically triggered.
authors.affiliation: Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg 41296, Sweden. Electronic address: xafenias@chalmers.se.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Xafenias
authors.affiliation: Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg 41296, Sweden; Faculty of Life Sciences, TU Braunschweig, Braunschweig 38160, Germany.
authors.forename: Cathleen
authors.initials: C
authors.lastname: Kmezik
authors.affiliation: Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg 41296, Sweden.
authors.forename: Valeria
authors.initials: V
authors.lastname: Mapelli
mesh_terms: D000085:Acetates / Q000378:metabolism*; D064751:Ammonium Compounds / Q000032:analysis; D048230:Corynebacterium glutamicum / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D004560:Electricity; D004563:Electrochemistry; D004566:Electrodes; D005285:Fermentation / Q000187:drug effects; D005561:Formates / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D008239:Lysine / Q000096:biosynthesis; D055442:Metabolome / Q000187:drug effects; D009566:Nitrates / Q000494:pharmacology*; D009573:Nitrites / Q000032:analysis; D010084:Oxidation-Reduction
chemical_list: D000085:Acetates; D064751:Ammonium Compounds; D005561:Formates; D009566:Nitrates; D009573:Nitrites; D005947:Glucose; D008239:Lysine
keywords: Acetate; Biocathodes; Corynebacterium glutamicum; Formate; Nitrate reduction