Enhanced Butanol Production Obtained by Reinforcing the Direct Butanol-Forming Route in <named-content content-type="genus-species">Clostridium acetobutylicum</named-content>

ABSTRACT Butanol is an important industrial solvent and advanced biofuel that can be produced by biphasic fermentation by Clostridium acetobutylicum. It has been known that acetate and butyrate first formed during the acidogenic phase are reassimilated to form acetone-butanol-ethanol (cold channel)....

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Autores principales: Yu-Sin Jang, Jin Young Lee, Joungmin Lee, Jin Hwan Park, Jung Ae Im, Moon-Ho Eom, Julia Lee, Sang-Hyun Lee, Hyohak Song, Jung-Hee Cho, Do Young Seung, Sang Yup Lee
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Publicado: American Society for Microbiology 2012
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spelling oai:doaj.org-article:95fb4c81fa5543f69477a21e1c93455e2021-11-15T15:39:12ZEnhanced Butanol Production Obtained by Reinforcing the Direct Butanol-Forming Route in <named-content content-type="genus-species">Clostridium acetobutylicum</named-content>10.1128/mBio.00314-122150-7511https://doaj.org/article/95fb4c81fa5543f69477a21e1c93455e2012-11-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00314-12https://doaj.org/toc/2150-7511ABSTRACT Butanol is an important industrial solvent and advanced biofuel that can be produced by biphasic fermentation by Clostridium acetobutylicum. It has been known that acetate and butyrate first formed during the acidogenic phase are reassimilated to form acetone-butanol-ethanol (cold channel). Butanol can also be formed directly from acetyl-coenzyme A (CoA) through butyryl-CoA (hot channel). However, little is known about the relative contributions of the two butanol-forming pathways. Here we report that the direct butanol-forming pathway is a better channel to optimize for butanol production through metabolic flux and mass balance analyses. Butanol production through the hot channel was maximized by simultaneous disruption of the pta and buk genes, encoding phosphotransacetylase and butyrate kinase, while the adhE1D485G gene, encoding a mutated aldehyde/alcohol dehydrogenase, was overexpressed. The ratio of butanol produced through the hot channel to that produced through the cold channel increased from 2.0 in the wild type to 18.8 in the engineered BEKW(pPthlAAD**) strain. By reinforcing the direct butanol-forming flux in C. acetobutylicum, 18.9 g/liter of butanol was produced, with a yield of 0.71 mol butanol/mol glucose by batch fermentation, levels which are 160% and 245% higher than those obtained with the wild type. By fed-batch culture of this engineered strain with in situ recovery, 585.3 g of butanol was produced from 1,861.9 g of glucose, with the yield of 0.76 mol butanol/mol glucose and productivity of 1.32 g/liter/h. Studies of two butanol-forming routes and their effects on butanol production in C. acetobutylicum described here will serve as a basis for further metabolic engineering of clostridia aimed toward developing a superior butanol producer. IMPORTANCE Renewable biofuel is one of the answers to solving the energy crisis and climate change problems. Butanol produced naturally by clostridia has superior liquid fuel characteristics and thus has the potential to replace gasoline. Due to the lack of efficient genetic manipulation tools, however, strain improvement has been rather slow. Furthermore, complex metabolic characteristics of acidogenesis followed by solventogenesis in this strain have hampered development of engineered clostridia having highly efficient and selective butanol production capability. Here we report for the first time the results of systems metabolic engineering studies of two butanol-forming routes and their relative importances in butanol production. Based on these findings, a metabolically engineered Clostridium acetobutylicum strain capable of producing butanol to a high titer with high yield and selectivity could be developed by reinforcing the direct butanol-forming flux.Yu-Sin JangJin Young LeeJoungmin LeeJin Hwan ParkJung Ae ImMoon-Ho EomJulia LeeSang-Hyun LeeHyohak SongJung-Hee ChoDo Young SeungSang Yup LeeAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 3, Iss 5 (2012)
institution DOAJ
collection DOAJ
language EN
topic Microbiology
QR1-502
spellingShingle Microbiology
QR1-502
Yu-Sin Jang
Jin Young Lee
Joungmin Lee
Jin Hwan Park
Jung Ae Im
Moon-Ho Eom
Julia Lee
Sang-Hyun Lee
Hyohak Song
Jung-Hee Cho
Do Young Seung
Sang Yup Lee
Enhanced Butanol Production Obtained by Reinforcing the Direct Butanol-Forming Route in <named-content content-type="genus-species">Clostridium acetobutylicum</named-content>
description ABSTRACT Butanol is an important industrial solvent and advanced biofuel that can be produced by biphasic fermentation by Clostridium acetobutylicum. It has been known that acetate and butyrate first formed during the acidogenic phase are reassimilated to form acetone-butanol-ethanol (cold channel). Butanol can also be formed directly from acetyl-coenzyme A (CoA) through butyryl-CoA (hot channel). However, little is known about the relative contributions of the two butanol-forming pathways. Here we report that the direct butanol-forming pathway is a better channel to optimize for butanol production through metabolic flux and mass balance analyses. Butanol production through the hot channel was maximized by simultaneous disruption of the pta and buk genes, encoding phosphotransacetylase and butyrate kinase, while the adhE1D485G gene, encoding a mutated aldehyde/alcohol dehydrogenase, was overexpressed. The ratio of butanol produced through the hot channel to that produced through the cold channel increased from 2.0 in the wild type to 18.8 in the engineered BEKW(pPthlAAD**) strain. By reinforcing the direct butanol-forming flux in C. acetobutylicum, 18.9 g/liter of butanol was produced, with a yield of 0.71 mol butanol/mol glucose by batch fermentation, levels which are 160% and 245% higher than those obtained with the wild type. By fed-batch culture of this engineered strain with in situ recovery, 585.3 g of butanol was produced from 1,861.9 g of glucose, with the yield of 0.76 mol butanol/mol glucose and productivity of 1.32 g/liter/h. Studies of two butanol-forming routes and their effects on butanol production in C. acetobutylicum described here will serve as a basis for further metabolic engineering of clostridia aimed toward developing a superior butanol producer. IMPORTANCE Renewable biofuel is one of the answers to solving the energy crisis and climate change problems. Butanol produced naturally by clostridia has superior liquid fuel characteristics and thus has the potential to replace gasoline. Due to the lack of efficient genetic manipulation tools, however, strain improvement has been rather slow. Furthermore, complex metabolic characteristics of acidogenesis followed by solventogenesis in this strain have hampered development of engineered clostridia having highly efficient and selective butanol production capability. Here we report for the first time the results of systems metabolic engineering studies of two butanol-forming routes and their relative importances in butanol production. Based on these findings, a metabolically engineered Clostridium acetobutylicum strain capable of producing butanol to a high titer with high yield and selectivity could be developed by reinforcing the direct butanol-forming flux.
format article
author Yu-Sin Jang
Jin Young Lee
Joungmin Lee
Jin Hwan Park
Jung Ae Im
Moon-Ho Eom
Julia Lee
Sang-Hyun Lee
Hyohak Song
Jung-Hee Cho
Do Young Seung
Sang Yup Lee
author_facet Yu-Sin Jang
Jin Young Lee
Joungmin Lee
Jin Hwan Park
Jung Ae Im
Moon-Ho Eom
Julia Lee
Sang-Hyun Lee
Hyohak Song
Jung-Hee Cho
Do Young Seung
Sang Yup Lee
author_sort Yu-Sin Jang
title Enhanced Butanol Production Obtained by Reinforcing the Direct Butanol-Forming Route in <named-content content-type="genus-species">Clostridium acetobutylicum</named-content>
title_short Enhanced Butanol Production Obtained by Reinforcing the Direct Butanol-Forming Route in <named-content content-type="genus-species">Clostridium acetobutylicum</named-content>
title_full Enhanced Butanol Production Obtained by Reinforcing the Direct Butanol-Forming Route in <named-content content-type="genus-species">Clostridium acetobutylicum</named-content>
title_fullStr Enhanced Butanol Production Obtained by Reinforcing the Direct Butanol-Forming Route in <named-content content-type="genus-species">Clostridium acetobutylicum</named-content>
title_full_unstemmed Enhanced Butanol Production Obtained by Reinforcing the Direct Butanol-Forming Route in <named-content content-type="genus-species">Clostridium acetobutylicum</named-content>
title_sort enhanced butanol production obtained by reinforcing the direct butanol-forming route in <named-content content-type="genus-species">clostridium acetobutylicum</named-content>
publisher American Society for Microbiology
publishDate 2012
url https://doaj.org/article/95fb4c81fa5543f69477a21e1c93455e
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