title: Model-guided metabolic gene knockout of gnd for enhanced succinate production in Escherichia coli from glucose and glycerol substrates.
abstract: The metabolic role of 6-phosphogluconate dehydrogenase (gnd) under anaerobic conditions with respect to succinate production in Escherichia coli remained largely unspecified. Herein we report what are to our knowledge the first metabolic gene knockout of gnd to have increased succinic acid production using both glucose and glycerol substrates in E. coli. Guided by a genome scale metabolic model, we engineered the E. coli host metabolism to enhance anaerobic production of succinic acid by deleting the gnd gene, considering its location in the boundary of oxidative and non-oxidative pentose phosphate pathway. This strategy induced either the activation of malic enzyme, causing up-regulation of phosphoenolpyruvate carboxylase (ppc) and down regulation of phosphoenolpyruvate carboxykinase (ppck) and/or prevents the decarboxylation of 6 phosphogluconate to increase the pool of glyceraldehyde-3-phosphate (GAP) that is required for the formation of phosphoenolpyruvate (PEP). This approach produced a mutant strain BMS2 with succinic acid production titers of 0.35 g l(-1) and 1.40 g l(-1) from glucose and glycerol substrates respectively. This work further clearly elucidates and informs other studies that the gnd gene, is a novel deletion target for increasing succinate production in E. coli under anaerobic condition using glucose and glycerol carbon sources. The knowledge gained in this study would help in E. coli and other microbial strains development for increasing succinate production and/or other industrial chemicals.
authors.affiliation: Bioinformatics Research Group (BIRG), Department of Biosciences and Health Sciences, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Skudai Johor Bahru, Malaysia. Electronic address: bashirmienda@fbb.utm.my.
authors.forename: Bashir Sajo
authors.initials: BS
authors.lastname: Mienda
authors.affiliation: Bioinformatics Research Group (BIRG), Department of Biosciences and Health Sciences, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Skudai Johor Bahru, Malaysia.
authors.forename: Mohd Shahir
authors.initials: MS
authors.lastname: Shamsir
authors.affiliation: Department of Bioprocess Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru, Malaysia.
authors.forename: Rosli Md
authors.initials: RM
authors.lastname: Illias
mesh_terms: D004926:Escherichia coli / Q000235:genetics*; D055785:Gene Knockdown Techniques; D005947:Glucose / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism*; D019802:Succinic Acid / Q000378:metabolism*
chemical_list: D019802:Succinic Acid; D005947:Glucose; D005990:Glycerol
keywords: 6-Phosphogluconate dehydrogenase (gnd); E. coli; Glucose; Glycerol; Metabolic gene knockout; OptFlux software; Pentose phosphate pathway; Succinate