Abstract:Production of 1,3-propanediol (1,3-PDO) from glycerol is a promising route toward glycerol biorefinery. However, the yield of 1,3-PDO is limited due to the requirement of NADH regeneration via glycerol oxidation process, which generates large amounts of undesired byproducts. Glutamate fermentation by Corynebacterium glutamicum is an important oxidation process generating excess NADH. In this study, we proposed a novel strategy to couple the process of 1,3-PDO synthesis with glutamate production for cofactor re… Show more
“…The resulting strain produced 1,3-PDO more rapidly during batch fermentation with a molar yield of 0.76 mol mol −1 glycerol. This yield was superior to those reported in other studies, which have reported molar yields of up to 0.66 mol mol −1 glycerol (Table 1 ) [ 10 , 15 , 16 ]. Fig.…”
BackgroundGlycerol is a major byproduct of the biodiesel industry and can be converted to 1,3-propanediol (1,3-PDO) by microorganisms through a two-step enzymatic reaction. The production of 1,3-PDO from glycerol using microorganisms is accompanied by formation of unwanted byproducts, including lactate and 2,3-butanediol, resulting in a low-conversion yield.ResultsKlebsiella pneumoniae was metabolically engineered to produce high-molar yield of 1,3-PDO from glycerol. First, the pathway genes for byproduct formation were deleted in K. pneumoniae. Then, glycerol assimilation pathways were eliminated and mannitol was co-fed to the medium. Finally, transcriptional regulation of the dha operon were genetically modified for enhancing 1,3-propanediol production. The batch fermentation of the engineered strain with co-feeding of a small amount of mannitol yielded 0.76 mol 1,3-PDO from 1 mol glycerol.ConclusionsKlebsiella pneumoniae is useful microorganism for producing 1,3-PDO from glycerol. Implemented engineering in this study successfully improved 1,3-PDO production yield, which is significantly higher than those reported in previous studies.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1100-5) contains supplementary material, which is available to authorized users.
“…The resulting strain produced 1,3-PDO more rapidly during batch fermentation with a molar yield of 0.76 mol mol −1 glycerol. This yield was superior to those reported in other studies, which have reported molar yields of up to 0.66 mol mol −1 glycerol (Table 1 ) [ 10 , 15 , 16 ]. Fig.…”
BackgroundGlycerol is a major byproduct of the biodiesel industry and can be converted to 1,3-propanediol (1,3-PDO) by microorganisms through a two-step enzymatic reaction. The production of 1,3-PDO from glycerol using microorganisms is accompanied by formation of unwanted byproducts, including lactate and 2,3-butanediol, resulting in a low-conversion yield.ResultsKlebsiella pneumoniae was metabolically engineered to produce high-molar yield of 1,3-PDO from glycerol. First, the pathway genes for byproduct formation were deleted in K. pneumoniae. Then, glycerol assimilation pathways were eliminated and mannitol was co-fed to the medium. Finally, transcriptional regulation of the dha operon were genetically modified for enhancing 1,3-propanediol production. The batch fermentation of the engineered strain with co-feeding of a small amount of mannitol yielded 0.76 mol 1,3-PDO from 1 mol glycerol.ConclusionsKlebsiella pneumoniae is useful microorganism for producing 1,3-PDO from glycerol. Implemented engineering in this study successfully improved 1,3-PDO production yield, which is significantly higher than those reported in previous studies.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1100-5) contains supplementary material, which is available to authorized users.
“…1,3-PDO and d- lactate are both valuable products which can be easily separated in the downstream process, and therefore the co-production strategy potentially revitalizes the whole biorefinery process with the higher atomic economy and the lower production cost. We also proposed a similar approach for the co-production of 1,3-PDO with glutamate using glycerol and glucose as co-substrates [ 54 ]. Glutamate is synthesized from glucose with the generation of extra NADH for 1,3-PDO formation from glycerol.…”
Section: Metabolic Engineering For the Production Of C3 Diolsmentioning
C2–C4 diols classically derived from fossil resource are very important bulk chemicals which have been used in a wide range of areas, including solvents, fuels, polymers, cosmetics, and pharmaceuticals. Production of C2–C4 diols from renewable resources has received significant interest in consideration of the reducing fossil resource and the increasing environmental issues. While bioproduction of certain diols like 1,3-propanediol has been commercialized in recent years, biosynthesis of many other important C2–C4 diol isomers is highly challenging due to the lack of natural synthesis pathways. Recent advances in synthetic biology have enabled the de novo design of completely new pathways to non-natural molecules from renewable feedstocks. In this study, we review recent advances in bioproduction of C2–C4 diols, focusing on new metabolic pathways and metabolic engineering strategies being developed. We also discuss the challenges and future trends toward the development of economically competitive processes for bio-based diol production.
“…Corynebacterium glutamicum , an aerobic gram-positive actinomycete capable of secreting glutamate under biotin limitation or in the presence of penicillin, has long-term applications in the industrial production of various valuable metabolites, including amino acids besides glutamate such as arginine, lysine, ornithine, and alanine [ 1 – 4 ]; diamines such as putrescine [ 5 , 6 ] and cadaverine [ 7 ]; dicarboxylic acids such as succinate [ 8 – 10 ]; diols such as 1,3-propanediol [ 11 ] and 1,2-propanediol [ 12 ]; and terpenes such as pinene and carotenoid [ 13 ]. Corynebacterium glutamicum S9114, a subspecies of C. glutamicum derived from Brevibacterium tianjinese T6–13 [ 14 ], has been widely used for glutamate fermentation in China.…”
Background
l-Ornithine is a non-protein amino acid with extensive applications in medicine and the food industry. Currently, l-ornithine production is based on microbial fermentation, and few microbes are used for producing l-ornithine owing to unsatisfactory production titer.ResultsIn this study, Corynebacterium glutamicum S9114, a high glutamate-producing strain, was developed for l-ornithine production by pathway engineering. First, argF was deleted to block l-ornithine to citrulline conversion. To improve l-ornithine production, ncgl1221 encoding glutamate transporter, argR encoding arginine repressor, and putP encoding proline transporter were disrupted. This base strain was further engineered by attenuating oxoglutarate dehydrogenase to increase l-ornithine production. Plasmid-based overexpression of argCJBD operon and lysine/arginine transport protein LysE was tested to strengthen l-ornithine synthesis and transportation. This resulted in efficient l-ornithine production at a titer of 18.4 g/L.ConclusionThese results demonstrate the potential of Corynebacterium glutamicum S9114 for efficient l-ornithine production and provide new targets for strain development.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-017-0776-8) contains supplementary material, which is available to authorized users.
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