Dataset Information

Improved production of 2,3-butanediol and isobutanol by engineering electron transport chain in Escherichia coli.

ABSTRACT: The electron transport chain (ETC) is one of the major energy generation pathways in microorganisms under aerobic condition. Higher yield of ATP can be achieved through oxidative phosphorylation with consumption of NADH than with substrate level phosphorylation. However, most value-added metabolites are in an electrochemically reduced state, which requires reducing equivalent NADH as a cofactor. Therefore, optimal production of value-added metabolites should be balanced with ETC in terms of energy production. In this study, we attempted to reduce the activity of ETC to secure availability of NADH. The ETC mutants exhibited poor growth rate and production of fermentative metabolites compared to parental strain. Introduction of heterologous pathways for synthesis of 2,3-butanediol and isobutanol to ETC mutants resulted in increased titres and yields of the metabolites. ETC mutants yielded higher NADH/NAD⁺ ratio but similar ATP content than that by the parental strain. Furthermore, ETC mutants operated fermentative metabolism pathways independent of oxygen supply in large-scale fermenter, resulting in increased yield and titre of 2,3-butanediol. Thus, engineering of ETC is a useful metabolic engineering approach for production of reduced metabolites.

SUBMITTER: Jung HM

PROVIDER: S-EPMC7888471 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Improved production of 2,3-butanediol and isobutanol by engineering electron transport chain in Escherichia coli.

Jung Hwi-Min HM Han Jae-Ho JH Oh Min-Kyu MK

Microbial biotechnology 20200920 1

The electron transport chain (ETC) is one of the major energy generation pathways in microorganisms under aerobic condition. Higher yield of ATP can be achieved through oxidative phosphorylation with consumption of NADH than with substrate level phosphorylation. However, most value-added metabolites are in an electrochemically reduced state, which requires reducing equivalent NADH as a cofactor. Therefore, optimal production of value-added metabolites should be balanced with ETC in terms of ener ...[more]

PMID: 32954676

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Project description:BackgroundPreviously, a safe strain, Bacillus amyloliquefaciens B10-127 was identified as an excellent candidate for industrial-scale microbial fermentation of 2,3-butanediol (2,3-BD). However, B. amyloliquefaciens fermentation yields large quantities of acetoin, lactate and succinate as by-products, and the 2,3-BD yield remains prohibitively low for commercial production.Methodology/principal findingsIn the 2,3-butanediol metabolic pathway, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) catalyzes the conversion of 3-phosphate glyceraldehyde to 1,3-bisphosphoglycerate, with concomitant reduction of NAD(+) to NADH. In the same pathway, 2,3-BD dehydrogenase (BDH) catalyzes the conversion of acetoin to 2,3-BD with concomitant oxidation of NADH to NAD(+). In this study, to improve 2,3-BD production, we first over-produced NAD(+)-dependent GAPDH and NADH-dependent BDH in B. amyloliquefaciens. Excess GAPDH reduced the fermentation time, increased the 2,3-BD yield by 12.7%, and decreased the acetoin titer by 44.3%. However, the process also enhanced lactate and succinate production. Excess BDH increased the 2,3-BD yield by 16.6% while decreasing acetoin, lactate and succinate production, but prolonged the fermentation time. When BDH and GAPDH were co-overproduced in B. amyloliquefaciens, the fermentation time was reduced. Furthermore, in the NADH-dependent pathways, the molar yield of 2,3-BD was increased by 22.7%, while those of acetoin, lactate and succinate were reduced by 80.8%, 33.3% and 39.5%, relative to the parent strain. In fed-batch fermentations, the 2,3-BD concentration was maximized at 132.9 g/l after 45 h, with a productivity of 2.95 g/l·h.Conclusions/significanceCo-overexpression of bdh and gapA genes proved an effective method for enhancing 2,3-BD production and inhibiting the accumulation of unwanted by-products (acetoin, lactate and succinate). To our knowledge, we have attained the highest 2,3-BD fermentation yield thus far reported for safe microorganisms.

Dataset Information

Improved production of 2,3-butanediol and isobutanol by engineering electron transport chain in Escherichia coli.

Publications

Improved production of 2,3-butanediol and isobutanol by engineering electron transport chain in Escherichia coli.

Similar Datasets

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