1
|
Pan H, Wang J, Wu H, Li Z, Lian J. Synthetic biology toolkit for engineering Cupriviadus necator H16 as a platform for CO 2 valorization. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:212. [PMID: 34736496 PMCID: PMC8570001 DOI: 10.1186/s13068-021-02063-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 10/25/2021] [Indexed: 06/09/2023]
Abstract
BACKGROUND CO2 valorization is one of the effective methods to solve current environmental and energy problems, in which microbial electrosynthesis (MES) system has proved feasible and efficient. Cupriviadus necator (Ralstonia eutropha) H16, a model chemolithoautotroph, is a microbe of choice for CO2 conversion, especially with the ability to be employed in MES due to the presence of genes encoding [NiFe]-hydrogenases and all the Calvin-Benson-Basham cycle enzymes. The CO2 valorization strategy will make sense because the required hydrogen can be produced from renewable electricity independently of fossil fuels. MAIN BODY In this review, synthetic biology toolkit for C. necator H16, including genetic engineering vectors, heterologous gene expression elements, platform strain and genome engineering, and transformation strategies, is firstly summarized. Then, the review discusses how to apply these tools to make C. necator H16 an efficient cell factory for converting CO2 to value-added products, with the examples of alcohols, fatty acids, and terpenoids. The review is concluded with the limitation of current genetic tools and perspectives on the development of more efficient and convenient methods as well as the extensive applications of C. necator H16. CONCLUSIONS Great progress has been made on genetic engineering toolkit and synthetic biology applications of C. necator H16. Nevertheless, more efforts are expected in the near future to engineer C. necator H16 as efficient cell factories for the conversion of CO2 to value-added products.
Collapse
Affiliation(s)
- Haojie Pan
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Jia Wang
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Haoliang Wu
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Zhongjian Li
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Jiazhang Lian
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China.
- Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, 310027, China.
| |
Collapse
|
2
|
Saaret A, Villiers B, Stricher F, Anissimova M, Cadillon M, Spiess R, Hay S, Leys D. Directed evolution of prenylated FMN-dependent Fdc supports efficient in vivo isobutene production. Nat Commun 2021; 12:5300. [PMID: 34489427 PMCID: PMC8421414 DOI: 10.1038/s41467-021-25598-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 07/29/2021] [Indexed: 11/30/2022] Open
Abstract
Isobutene is a high value gaseous alkene used as fuel additive and a chemical building block. As an alternative to fossil fuel derived isobutene, we here develop a modified mevalonate pathway for the production of isobutene from glucose in vivo. The final step in the pathway consists of the decarboxylation of 3-methylcrotonic acid, catalysed by an evolved ferulic acid decarboxylase (Fdc) enzyme. Fdc belongs to the prFMN-dependent UbiD enzyme family that catalyses reversible decarboxylation of (hetero)aromatic acids or acrylic acids with extended conjugation. Following a screen of an Fdc library for inherent 3-methylcrotonic acid decarboxylase activity, directed evolution yields variants with up to an 80-fold increase in activity. Crystal structures of the evolved variants reveal that changes in the substrate binding pocket are responsible for increased selectivity. Solution and computational studies suggest that isobutene cycloelimination is rate limiting and strictly dependent on presence of the 3-methyl group. Isobutene is a high value gaseous alkene that is widely used as fuel additive and a chemical building block. Here, the authors report an alternative pathway for isobutene bioproduction by directed evolution of prenylated FMN-dependent ferulic acid decarboxylase.
Collapse
Affiliation(s)
- Annica Saaret
- Department of Chemistry, Manchester Institute for Biotechnology, University of Manchester, Manchester, UK
| | | | | | | | | | - Reynard Spiess
- Department of Chemistry, Manchester Institute for Biotechnology, University of Manchester, Manchester, UK
| | - Sam Hay
- Department of Chemistry, Manchester Institute for Biotechnology, University of Manchester, Manchester, UK
| | - David Leys
- Department of Chemistry, Manchester Institute for Biotechnology, University of Manchester, Manchester, UK.
| |
Collapse
|
3
|
Mustila H, Kugler A, Stensjö K. Isobutene production in Synechocystis sp. PCC 6803 by introducing α-ketoisocaproate dioxygenase from Rattus norvegicus. Metab Eng Commun 2021; 12:e00163. [PMID: 33552898 PMCID: PMC7856465 DOI: 10.1016/j.mec.2021.e00163] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 01/12/2021] [Accepted: 01/18/2021] [Indexed: 12/28/2022] Open
Abstract
Cyanobacteria can be utilized as a platform for direct phototrophic conversion of CO2 to produce several types of carbon-neutral biofuels. One promising compound to be produced photobiologically in cyanobacteria is isobutene. As a volatile compound, isobutene will quickly escape the cells without building up to toxic levels in growth medium or get caught in the membranes. Unlike liquid biofuels, gaseous isobutene may be collected from the headspace and thus avoid the costly extraction of a chemical from culture medium or from cells. Here we investigate a putative synthetic pathway for isobutene production suitable for a photoautotrophic host. First, we expressed α-ketoisocaproate dioxygenase from Rattus norvegicus (RnKICD) in Escherichia coli. We discovered isobutene formation with the purified RnKICD with the rate of 104.6 ± 9 ng (mg protein)-1 min-1 using α-ketoisocaproate as a substrate. We further demonstrate isobutene production in the cyanobacterium Synechocystis sp. PCC 6803 by introducing the RnKICD enzyme. Synechocystis strain heterologously expressing the RnKICD produced 91 ng l−1 OD750−1 h−1. Thus, we demonstrate a novel sustainable platform for cyanobacterial production of an important building block chemical, isobutene. These results indicate that RnKICD can be used to further optimize the synthetic isobutene pathway by protein and metabolic engineering efforts. Photosynthetic isobutene production is demonstrated in a cyanobacterium. A Synechocystis strain capable of continuous direct conversion of CO2 to isobutene. α-ketoisocaproate dioxygenase from R. norvegicus (RnKICD) is determined to form isobutene. RnKICD can convert α-ketoisocaproate to isobutene both in vitro and in vivo.
Collapse
Affiliation(s)
- Henna Mustila
- Microbial Chemistry, Department of Chemistry-Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden
| | - Amit Kugler
- Microbial Chemistry, Department of Chemistry-Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden
| | - Karin Stensjö
- Microbial Chemistry, Department of Chemistry-Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden
| |
Collapse
|
4
|
Tian K, Li Q, Jiang W, Wang X, Liu S, Zhao Y, Zhou G. Effect of the pore structure of an active alumina catalyst on isobutene production by dehydration of isobutanol. RSC Adv 2021; 11:11952-11958. [PMID: 35423736 PMCID: PMC8697028 DOI: 10.1039/d1ra00136a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 03/12/2021] [Indexed: 12/31/2022] Open
Abstract
An alumina catalyst was prepared by mixing and pinching with pseudo-boehmite, and the catalyst was reamed with polyethylene glycol. The catalysts prepared were characterized by means of XRD, mercury injection and NH3-TPD, and the dehydration properties of the catalysts prepared with different amounts of reamer were evaluated in a 10 mL fixed bed reactor with 5% water as a raw material. The results showed that the addition of reamer did not affect the crystal structure and the amount of acid of the catalyst. With the increase of the amount of reamer, the pore volume of the catalyst increased continuously, the number of large pores increased, the conversion rate of isobutanol increased, and the selectivity of isobutene remained basically unchanged. When the amount of reamer is 30%, the isobutanol conversion rate is the best. The isobutanol conversion rate and the isobutene selectivity were 97% and 93% respectively under the conditions of 330 °C, 0.1 MPa and 12 h−1 air velocity of the body liquid. An alumina catalyst was prepared by mixing and pinching with pseudo-boehmite, and the catalyst was reamed with polyethylene glycol.![]()
Collapse
Affiliation(s)
- Kaige Tian
- College of New Energy and Materials
- China University of Petroleum-Beijing
- Beijing
- China
| | - Qin Li
- College of New Energy and Materials
- China University of Petroleum-Beijing
- Beijing
- China
| | - Weili Jiang
- College of New Energy and Materials
- China University of Petroleum-Beijing
- Beijing
- China
| | - Xiaosheng Wang
- College of New Energy and Materials
- China University of Petroleum-Beijing
- Beijing
- China
| | - Shicheng Liu
- College of New Energy and Materials
- China University of Petroleum-Beijing
- Beijing
- China
| | - Yapeng Zhao
- College of New Energy and Materials
- China University of Petroleum-Beijing
- Beijing
- China
| | - Guanglin Zhou
- College of New Energy and Materials
- China University of Petroleum-Beijing
- Beijing
- China
| |
Collapse
|
5
|
Rohwerder T, Rohde MT, Jehmlich N, Purswani J. Actinobacterial Degradation of 2-Hydroxyisobutyric Acid Proceeds via Acetone and Formyl-CoA by Employing a Thiamine-Dependent Lyase Reaction. Front Microbiol 2020; 11:691. [PMID: 32351493 PMCID: PMC7176365 DOI: 10.3389/fmicb.2020.00691] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 03/25/2020] [Indexed: 11/13/2022] Open
Abstract
The tertiary branched short-chain 2-hydroxyisobutyric acid (2-HIBA) has been associated with several metabolic diseases and lysine 2-hydroxyisobutyrylation seems to be a common eukaryotic as well as prokaryotic post-translational modification in proteins. In contrast, the underlying 2-HIBA metabolism has thus far only been detected in a few microorganisms, such as the betaproteobacterium Aquincola tertiaricarbonis L108 and the Bacillus group bacterium Kyrpidia tusciae DSM 2912. In these strains, 2-HIBA can be specifically activated to the corresponding CoA thioester by the 2-HIBA-CoA ligase (HCL) and is then isomerized to 3-hydroxybutyryl-CoA in a reversible and B12-dependent mutase reaction. Here, we demonstrate that the actinobacterial strain Actinomycetospora chiangmaiensis DSM 45062 degrades 2-HIBA and also its precursor 2-methylpropane-1,2-diol via acetone and formic acid by employing a thiamine pyrophosphate-dependent lyase. The corresponding gene is located directly upstream of hcl, which has previously been found only in operonic association with the 2-hydroxyisobutyryl-CoA mutase genes in other bacteria. Heterologous expression of the lyase gene from DSM 45062 in E. coli established a 2-hydroxyisobutyryl-CoA lyase activity in the latter. In line with this, analysis of the DSM 45062 proteome reveals a strong induction of the lyase-HCL gene cluster on 2-HIBA. Acetone is likely degraded via hydroxylation to acetol catalyzed by a MimABCD-related binuclear iron monooxygenase and formic acid appears to be oxidized to CO2 by selenium-dependent dehydrogenases. The presence of the lyase-HCL gene cluster in isoprene-degrading Rhodococcus strains and Pseudonocardia associated with tropical leafcutter ant species points to a role in degradation of biogenic short-chain ketones and highly branched organic compounds.
Collapse
Affiliation(s)
- Thore Rohwerder
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Maria-Teresa Rohde
- Institut für Chemie - Biophysikalische Chemie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany
| | - Nico Jehmlich
- Department of Molecular Systems Biology, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Jessica Purswani
- Institute of Water Research, University of Granada, Granada, Spain
| |
Collapse
|
6
|
Oki K, Lee FS, Mayo SL. Attempts to develop an enzyme converting DHIV to KIV. Protein Eng Des Sel 2019; 32:261-270. [PMID: 31872250 DOI: 10.1093/protein/gzz042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/01/2019] [Indexed: 11/13/2022] Open
Abstract
Dihydroxy-acid dehydratase (DHAD) catalyzes the dehydration of R-2,3-dihydroxyisovalerate (DHIV) to 2-ketoisovalerate (KIV) using an Fe-S cluster as a cofactor, which is sensitive to oxidation and expensive to synthesize. In contrast, sugar acid dehydratases catalyze the same chemical reactions using a magnesium ion. Here, we attempted to substitute the high-cost DHAD with a cost-efficient engineered sugar acid dehydratase using computational protein design (CPD). First, we tried without success to modify the binding pocket of a sugar acid dehydratase to accommodate the smaller, more hydrophobic DHIV. Then, we used a chemically activated substrate analog to react with sugar acid dehydratases or other enolase superfamily enzymes. Mandelate racemase from Pseudomonas putida (PpManR) and the putative sugar acid dehydratase from Salmonella typhimurium (StPutD) showed beta-elimination activity towards chlorolactate (CLD). CPD combined with medium-throughput selection improved the PpManR kcat/KM for CLD by four-fold. However, these enzyme variants did not show dehydration activity towards DHIV. Lastly, assuming phosphorylation could also be a good activation mechanism, we found that mevalonate-3-kinase (M3K) from Picrophilus torridus (PtM3K) exhibited adenosine triphosphate (ATP) hydrolysis activity when mixed with DHIV, indicating phosphorylation activity towards DHIV. Engineering PpManR or StPutD to accept 3-phospho-DHIV as a substrate was performed, but no variants with the desired activity were obtained.
Collapse
Affiliation(s)
- Kenji Oki
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., MC 114-96, Pasadena, CA 91125, USA.,Science & Innovation Center, Mitsubishi Chemical Corporation, Yokohama 227-8502, Japan
| | - Frederick S Lee
- Protabit LLC, 1010 Union St., Suite 110, Pasadena, CA 91101, USA
| | - Stephen L Mayo
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., MC 114-96, Pasadena, CA 91125, USA.,Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| |
Collapse
|
7
|
Wilson J, Gering S, Pinard J, Lucas R, Briggs BR. Bio-production of gaseous alkenes: ethylene, isoprene, isobutene. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:234. [PMID: 30181774 PMCID: PMC6114056 DOI: 10.1186/s13068-018-1230-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 08/17/2018] [Indexed: 05/05/2023]
Abstract
To reduce emissions from petrochemical refinement, bio-production has been heralded as a way to create economically valuable compounds with fewer harmful effects. For example, gaseous alkenes are precursor molecules that can be polymerized into a variety of industrially significant compounds and have biological production pathways. Production levels, however, remain low, thus enhancing bio-production of gaseous petrochemicals for chemical precursors is critical. This review covers the metabolic pathways and production levels of the gaseous alkenes ethylene, isoprene, and isobutene. Techniques needed to drive production to higher levels are also discussed.
Collapse
Affiliation(s)
- James Wilson
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508 USA
| | - Sarah Gering
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508 USA
| | - Jessica Pinard
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508 USA
| | - Ryan Lucas
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508 USA
| | - Brandon R. Briggs
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508 USA
| |
Collapse
|
8
|
Straathof AJJ, Cuellar MC. Microbial Hydrocarbon Formation from Biomass. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2017; 166:411-425. [PMID: 28707104 DOI: 10.1007/10_2016_62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Fossil carbon sources mainly contain hydrocarbons, and these are used on a huge scale as fuel and chemicals. Producing hydrocarbons from biomass instead is receiving increased attention. Achievable yields are modest because oxygen atoms need to be removed from biomass, keeping only the lighter carbon and hydrogen atoms. Microorganisms can perform the required conversions, potentially with high selectivity, using metabolic pathways that often end with decarboxylation. Metabolic and protein engineering are used successfully to achieve hydrocarbon production levels that are relevant in a biorefinery context. This has led to pilot or demo processes for hydrocarbons such as isobutene, isoprene, and farnesene. In addition, some non-hydrocarbon fermentation products are being further converted into hydrocarbons using a final chemical step, for example, ethanol into ethene. The main advantage of direct microbial production of hydrocarbons, however, is their potentially easy recovery because they do not dissolve in fermentation broth.
Collapse
Affiliation(s)
- Adrie J J Straathof
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ, Delft, The Netherlands.
| | - Maria C Cuellar
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| |
Collapse
|
9
|
Kang A, Meadows CW, Canu N, Keasling JD, Lee TS. High-throughput enzyme screening platform for the IPP-bypass mevalonate pathway for isopentenol production. Metab Eng 2017; 41:125-134. [DOI: 10.1016/j.ymben.2017.03.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/09/2017] [Accepted: 03/31/2017] [Indexed: 10/19/2022]
|
10
|
Kancharla P, Bonnett SA, Reynolds KA. Stenotrophomonas maltophilia OleC-Catalyzed ATP-Dependent Formation of Long-Chain Z-Olefins from 2-Alkyl-3-hydroxyalkanoic Acids. Chembiochem 2016; 17:1426-9. [PMID: 27238740 DOI: 10.1002/cbic.201600063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Indexed: 12/21/2022]
Abstract
The bacterial pathway of olefin biosynthesis starts with OleA catalyzed "head-to-head" condensation of two CoA-activated long-chain fatty acids to generate (R)-2-alkyl-3-ketoalkanoic acids. A subsequent OleD-catalyzed reduction generates (2R,3S)-2-alkyl-3-hydroxyalkanoic acids. We now show that the final step in the pathway is an OleC-catalyzed ATP-dependent decarboxylative dehydration to form the corresponding Z olefins. Higher kcat /Km values were seen for substrates with longer alkyl chains. All four stereoisomers of 2-hexyl-3-hydroxydecanoic acid were shown to be substrates, and GC-MS and NMR analyses confirmed that the product in each case was (Z)-pentadec-7-ene. LC-MS analysis supported the formation of AMP adduct as an intermediate. The enzymatic and stereochemical course of olefin biosynthesis from long-chain fatty acids by OleA, OleD and OleC is now established.
Collapse
Affiliation(s)
- Papireddy Kancharla
- Department of Chemistry, Portland State University, Portland, OR, 97201-3203, USA
| | - Shilah A Bonnett
- Department of Chemistry, Portland State University, Portland, OR, 97201-3203, USA
| | - Kevin A Reynolds
- Department of Chemistry, Portland State University, Portland, OR, 97201-3203, USA.
| |
Collapse
|
11
|
Isopentenyl diphosphate (IPP)-bypass mevalonate pathways for isopentenol production. Metab Eng 2016; 34:25-35. [DOI: 10.1016/j.ymben.2015.12.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/02/2015] [Accepted: 12/07/2015] [Indexed: 11/20/2022]
|
12
|
Abbassi S, Patel K, Khan B, Bhosale S, Gaikwad S. Functional and conformational transitions of mevalonate diphosphate decarboxylase from Bacopa monniera. Int J Biol Macromol 2015; 83:160-70. [PMID: 26657583 DOI: 10.1016/j.ijbiomac.2015.11.067] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 11/24/2015] [Accepted: 11/25/2015] [Indexed: 11/18/2022]
Abstract
Functional and conformational transitions of mevalonate diphosphate decarboxylase (MDD), a key enzyme of mevalonate pathway in isoprenoid biosynthesis, from Bacopa monniera (BmMDD), cloned and overexpressed in Escherichia coli were studied under thermal, chemical and pH-mediated denaturation conditions using fluorescence and Circular dichroism spectroscopy. Native BmMDD is a helix dominant structure with 45% helix and 11% sheets and possesses seven tryptophan residues with two residues exposed on surface, three residues partially exposed and two situated in the interior of the protein. Thermal denaturation of BmMDD causes rapid structural transitions at and above 40°C and transient exposure of hydrophobic residues at 50°C, leading to aggregation of the protein. An acid induced molten globule like structure was observed at pH 4, exhibiting altered but compact secondary structure, distorted tertiary structure and exposed hydrophobic residues. The molten globule displayed different response at higher temperature and similar response to chemical denaturation as compared to the native protein. The surface tryptophans have predominantly positively charged amino acids around them, as indicated by higher KSV for KI as compared to that for CsCl. The native enzyme displayed two different lifetimes, τ1 (1.203±0.036 ns) and τ2 (3.473±0.12 ns) indicating two populations of tryptophan.
Collapse
Affiliation(s)
- Shakeel Abbassi
- Plant Tissue Culture Division, National Chemical Laboratory, Pune 411008, India
| | - Krunal Patel
- Plant Tissue Culture Division, National Chemical Laboratory, Pune 411008, India
| | - Bashir Khan
- Plant Tissue Culture Division, National Chemical Laboratory, Pune 411008, India
| | - Siddharth Bhosale
- Division of Biochemical Sciences, National Chemical Laboratory, Pune 411008, India
| | - Sushama Gaikwad
- Division of Biochemical Sciences, National Chemical Laboratory, Pune 411008, India.
| |
Collapse
|
13
|
Chen X, Xu J, Yang L, Yuan Z, Xiao S, Zhang Y, Liang C, He M, Guo Y. Production of C4 and C5 branched-chain alcohols by engineered Escherichia. coli. J Ind Microbiol Biotechnol 2015; 42:1473-9. [PMID: 26350079 DOI: 10.1007/s10295-015-1656-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 07/22/2015] [Indexed: 11/26/2022]
Abstract
Higher alcohols, longer chain alcohols, contain more than 3 carbon atoms, showed close energy advantages as gasoline, and were considered as the next generation substitution for chemical fuels. Higher alcohol biosynthesis by native microorganisms mainly needs gene expression of heterologous keto acid decarboxylase and alcohol dehydrogenases. In the present study, branched-chain α-keto acid decarboxylase gene from Lactococcus lactis subsp. lactis CICC 6246 (Kivd) and alcohol dehydrogenases gene from Zymomonas mobilis CICC 41465 (AdhB) were transformed into Escherichia coli for higher alcohol production. SDS-PAGE results showed these two proteins were expressed in the recombinant strains. The resulting strain was incubated in LB medium at 37 °C in Erlenmeyer flasks and much more 3-methyl-1-butanol (104 mg/L) than isobutanol (24 mg/L) was produced. However, in 5 g/L glucose-containing medium, the production of two alcohols was similar, 156 and 161 mg/L for C4 (isobutanol) and C5 (3-methyl-1-butanol) alcohol, respectively. Effects of fermentation factors including temperature, glucose content, and α-keto acid on alcohol production were also investigated. The increase of glucose content and the adding of α-keto acids facilitated the production of C4 and C5 alcohols. The enzyme activities of pure Kivd on α-ketoisovalerate and α-ketoisocaproate were 26.77 and 21.24 μmol min(-1) mg(-1), respectively. Due to its ability on decarboxylation of α-ketoisovalerate and α-ketoisocaproate, the recombinant E. coli strain showed potential application on isoamyl alcohol and isobutanol production.
Collapse
Affiliation(s)
- Xiaoyan Chen
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Jingliang Xu
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Liu Yang
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Zhenhong Yuan
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China.
| | - Shiyuan Xiao
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Yu Zhang
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Cuiyi Liang
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Minchao He
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Ying Guo
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| |
Collapse
|
14
|
The Putative mevalonate diphosphate decarboxylase from Picrophilus torridus is in reality a mevalonate-3-kinase with high potential for bioproduction of isobutene. Appl Environ Microbiol 2015; 81:2625-34. [PMID: 25636853 PMCID: PMC4357925 DOI: 10.1128/aem.04033-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mevalonate diphosphate decarboxylase (MVD) is an ATP-dependent enzyme that catalyzes the phosphorylation/decarboxylation of (R)-mevalonate-5-diphosphate to isopentenyl pyrophosphate in the mevalonate (MVA) pathway. MVD is a key enzyme in engineered metabolic pathways for bioproduction of isobutene, since it catalyzes the conversion of 3-hydroxyisovalerate (3-HIV) to isobutene, an important platform chemical. The putative homologue from Picrophilus torridus has been identified as a highly efficient variant in a number of patents, but its detailed characterization has not been reported. In this study, we have successfully purified and characterized the putative MVD from P. torridus. We discovered that it is not a decarboxylase per se but an ATP-dependent enzyme, mevalonate-3-kinase (M3K), which catalyzes the phosphorylation of MVA to mevalonate-3-phosphate. The enzyme's potential in isobutene formation is due to the conversion of 3-HIV to an unstable 3-phosphate intermediate that undergoes consequent spontaneous decarboxylation to form isobutene. Isobutene production rates were as high as 507 pmol min−1 g cells−1 using Escherichia coli cells expressing the enzyme and 2,880 pmol min−1 mg protein−1 with the purified histidine-tagged enzyme, significantly higher than reported previously. M3K is a key enzyme of the novel MVA pathway discovered very recently in Thermoplasma acidophilum. We suggest that P. torridus metabolizes MVA by the same pathway.
Collapse
|
15
|
Metabolism of 2-methylpropene (isobutylene) by the aerobic bacterium Mycobacterium sp. strain ELW1. Appl Environ Microbiol 2015; 81:1966-76. [PMID: 25576605 DOI: 10.1128/aem.03103-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An aerobic bacterium (Mycobacterium sp. strain ELW1) that utilizes 2-methylpropene (isobutylene) as a sole source of carbon and energy was isolated and characterized. Strain ELW1 grew on 2-methylpropene (growth rate = 0.05 h(-1)) with a yield of 0.38 mg (dry weight) mg 2-methylpropene(-1). Strain ELW1 also grew more slowly on both cis- and trans-2-butene but did not grow on any other C2 to C5 straight-chain, branched, or chlorinated alkenes tested. Resting 2-methylpropene-grown cells consumed ethene, propene, and 1-butene without a lag phase. Epoxyethane accumulated as the only detected product of ethene oxidation. Both alkene consumption and epoxyethane production were fully inhibited in cells exposed to 1-octyne, suggesting that alkene oxidation is initiated by an alkyne-sensitive, epoxide-generating monooxygenase. Kinetic analyses indicated that 1,2-epoxy-2-methylpropane is rapidly consumed during 2-methylpropene degradation, while 2-methyl-2-propen-1-ol is not a significant metabolite of 2-methylpropene catabolism. Degradation of 1,2-epoxy-2-methylpropane by 2-methylpropene-grown cells led to the accumulation and further degradation of 2-methyl-1,2-propanediol and 2-hydroxyisobutyrate, two sequential metabolites previously identified in the aerobic microbial metabolism of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA). Growth of strain ELW1 on 2-methylpropene, 1,2-epoxy-2-methylpropane, 2-methyl-1,2-propanediol, and 2-hydroxyisobutyrate was fully inhibited when cobalt ions were omitted from the growth medium, while growth on 3-hydroxybutyrate and other substrates was unaffected by the absence of added cobalt ions. Our results suggest that, like aerobic MTBE- and TBA-metabolizing bacteria, strain ELW1 utilizes a cobalt/cobalamin-dependent mutase to transform 2-hydroxyisobutyrate. Our results have been interpreted in terms of their impact on our understanding of the microbial metabolism of alkenes and ether oxygenates.
Collapse
|
16
|
Korman TP, Sahachartsiri B, Li D, Vinokur JM, Eisenberg D, Bowie JU. A synthetic biochemistry system for the in vitro production of isoprene from glycolysis intermediates. Protein Sci 2014; 23:576-85. [PMID: 24623472 DOI: 10.1002/pro.2436] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 01/30/2014] [Accepted: 01/30/2014] [Indexed: 02/04/2023]
Abstract
The high yields required for the economical production of chemicals and fuels using microbes can be difficult to achieve due to the complexities of cellular metabolism. An alternative to performing biochemical transformations in microbes is to build biochemical pathways in vitro, an approach we call synthetic biochemistry. Here we test whether the full mevalonate pathway can be reconstituted in vitro and used to produce the commodity chemical isoprene. We construct an in vitro synthetic biochemical pathway that uses the carbon and ATP produced from the glycolysis intermediate phosphoenolpyruvate to run the mevalonate pathway. The system involves 12 enzymes to perform the complex transformation, while providing and balancing the ATP, NADPH, and acetyl-CoA cofactors. The optimized system produces isoprene from phosphoenolpyruvate in ∼100% molar yield. Thus, by inserting the isoprene pathway into previously developed glycolysis modules it may be possible to produce isoprene and other acetyl-CoA derived isoprenoids from glucose in vitro.
Collapse
Affiliation(s)
- Tyler P Korman
- Department of Chemistry and Biochemistry, UCLA-DOE Institute for Genomics and Proteomics, Molecular Biology Institute, University of California, Los Angeles, California
| | | | | | | | | | | |
Collapse
|
17
|
Liu Y, Wang C, Yan J, Zhang W, Guan W, Lu X, Li S. Hydrogen peroxide-independent production of α-alkenes by OleTJE P450 fatty acid decarboxylase. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:28. [PMID: 24565055 PMCID: PMC3937522 DOI: 10.1186/1754-6834-7-28] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 02/10/2014] [Indexed: 05/21/2023]
Abstract
BACKGROUND Cytochrome P450 OleTJE from Jeotgalicoccus sp. ATCC 8456, a new member of the CYP152 peroxygenase family, was recently found to catalyze the unusual decarboxylation of long-chain fatty acids to form α-alkenes using H2O2 as the sole electron and oxygen donor. Because aliphatic α-alkenes are important chemicals that can be used as biofuels to replace fossil fuels, or for making lubricants, polymers and detergents, studies on OleTJE fatty acid decarboxylase are significant and may lead to commercial production of biogenic α-alkenes in the future, which are renewable and more environmentally friendly than petroleum-derived equivalents. RESULTS We report the H2O2-independent activity of OleTJE for the first time. In the presence of NADPH and O2, this P450 enzyme efficiently decarboxylates long-chain fatty acids (C12 to C20) in vitro when partnering with either the fused P450 reductase domain RhFRED from Rhodococcus sp. or the separate flavodoxin/flavodoxin reductase from Escherichia coli. In vivo, expression of OleTJE or OleTJE-RhFRED in different E. coli strains overproducing free fatty acids resulted in production of variant levels of multiple α-alkenes, with a highest total hydrocarbon titer of 97.6 mg·l-1. CONCLUSIONS The discovery of the H2O2-independent activity of OleTJE not only raises a number of fundamental questions on the monooxygenase-like mechanism of this peroxygenase, but also will direct the future metabolic engineering work toward improvement of O2/redox partner(s)/NADPH for overproduction of α-alkenes by OleTJE.
Collapse
Affiliation(s)
- Yi Liu
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Cong Wang
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
| | - Jinyong Yan
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
| | - Wei Zhang
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
| | - Wenna Guan
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
| | - Xuefeng Lu
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
| | - Shengying Li
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
| |
Collapse
|
18
|
Kourist R, Guterl JK, Miyamoto K, Sieber V. Enzymatic Decarboxylation-An Emerging Reaction for Chemicals Production from Renewable Resources. ChemCatChem 2014. [DOI: 10.1002/cctc.201300881] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
19
|
Eikmanns BJ, Blombach B. The pyruvate dehydrogenase complex of Corynebacterium glutamicum: an attractive target for metabolic engineering. J Biotechnol 2014; 192 Pt B:339-45. [PMID: 24486441 DOI: 10.1016/j.jbiotec.2013.12.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 12/12/2013] [Accepted: 12/16/2013] [Indexed: 11/18/2022]
Abstract
The pyruvate dehydrogenase complex (PDHC) catalyzes the oxidative thiamine pyrophosphate-dependent decarboxylation of pyruvate to acetyl-CoA and CO2. Since pyruvate is a key metabolite of the central metabolism and also the precursor for several relevant biotechnological products, metabolic engineering of this multienzyme complex is a promising strategy to improve microbial production processes. This review summarizes the current knowledge and achievements on metabolic engineering approaches to tailor the PDHC of Corynebacterium glutamicum for the bio-based production of l-valine, 2-ketosiovalerate, pyruvate, succinate and isobutanol and to improve l-lysine production.
Collapse
Affiliation(s)
- Bernhard J Eikmanns
- Institute of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany
| | - Bastian Blombach
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany.
| |
Collapse
|
20
|
Straathof AJJ. Transformation of Biomass into Commodity Chemicals Using Enzymes or Cells. Chem Rev 2013; 114:1871-908. [DOI: 10.1021/cr400309c] [Citation(s) in RCA: 315] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Adrie J. J. Straathof
- Department of Biotechnology, Delft University of Technology, Julianalaan
67, 2628
BC Delft, The Netherlands
| |
Collapse
|
21
|
Min K, Kim S, Yum T, Kim Y, Sang BI, Um Y. Conversion of levulinic acid to 2-butanone by acetoacetate decarboxylase from Clostridium acetobutylicum. Appl Microbiol Biotechnol 2013; 97:5627-34. [PMID: 23624707 DOI: 10.1007/s00253-013-4879-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 03/21/2013] [Accepted: 03/22/2013] [Indexed: 10/26/2022]
Abstract
In this study, a novel system for synthesis of 2-butanone from levulinic acid (γ-keto-acid) via an enzymatic reaction was developed. Acetoacetate decarboxylase (AADC; E.C. 4.1.1.4) from Clostridium acetobutylicum was selected as a biocatalyst for decarboxylation of levulinic acid. The purified recombinant AADC from Escherichia coli successfully converted levulinic acid to 2-butanone with a conversion yield of 8.4-90.3 % depending on the amount of AADC under optimum conditions (30 °C and pH 5.0) despite that acetoacetate, a β-keto-acid, is a natural substrate of AADC. In order to improve the catalytic efficiency, an AADC-mediator system was tested using methyl viologen, methylene blue, azure B, zinc ion, and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) as mediators. Among them, methyl viologen showed the best performance, increasing the conversion yield up to 6.7-fold in comparison to that without methyl viologen. The results in this study are significant in the development of a renewable method for the synthesis of 2-butanone from biomass-derived chemical, levulinic acid, through enzymatic decarboxylation.
Collapse
Affiliation(s)
- Kyoungseon Min
- Clean Energy Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791, South Korea
| | | | | | | | | | | |
Collapse
|
22
|
Lu J, Brigham CJ, Gai CS, Sinskey AJ. Studies on the production of branched-chain alcohols in engineered Ralstonia eutropha. Appl Microbiol Biotechnol 2012; 96:283-97. [DOI: 10.1007/s00253-012-4320-9] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 07/16/2012] [Accepted: 07/17/2012] [Indexed: 11/25/2022]
|
23
|
van Leeuwen BNM, van der Wulp AM, Duijnstee I, van Maris AJA, Straathof AJJ. Fermentative production of isobutene. Appl Microbiol Biotechnol 2012; 93:1377-87. [PMID: 22234536 PMCID: PMC3275743 DOI: 10.1007/s00253-011-3853-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 12/18/2011] [Accepted: 12/20/2011] [Indexed: 11/30/2022]
Abstract
Isobutene (2-methylpropene) is one of those chemicals for which bio-based production might replace the petrochemical production in the future. Currently, more than 10 million metric tons of isobutene are produced on a yearly basis. Even though bio-based production might also be achieved through chemocatalytic or thermochemical methods, this review focuses on fermentative routes from sugars. Although biological isobutene formation is known since the 1970s, extensive metabolic engineering is required to achieve economically viable yields and productivities. Two recent metabolic engineering developments may enable anaerobic production close to the theoretical stoichiometry of 1isobutene + 2CO(2) + 2H(2)O per mol of glucose. One relies on the conversion of 3-hydroxyisovalerate to isobutene as a side activity of mevalonate diphosphate decarboxylase and the other on isobutanol dehydration as a side activity of engineered oleate hydratase. The latter resembles the fermentative production of isobutanol followed by isobutanol recovery and chemocatalytic dehydration. The advantage of a completely biological route is that not isobutanol, but instead gaseous isobutene is recovered from the fermenter together with CO(2). The low aqueous solubility of isobutene might also minimize product toxicity to the microorganisms. Although developments are at their infancy, the potential of a large scale fermentative isobutene production process is assessed. The production costs estimate is 0.9 Euro kg(-1), which is reasonably competitive. About 70% of the production costs will be due to the costs of lignocellulose hydrolysate, which seems to be a preferred feedstock.
Collapse
Affiliation(s)
- Bianca N. M. van Leeuwen
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
| | - Albertus M. van der Wulp
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
| | - Isabelle Duijnstee
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
| | - Antonius J. A. van Maris
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
- Kluyver Centre for Genomics of Industrial Fermentation, Julianalaan 67, 2628 BC Delft, The Netherlands
| | - Adrie J. J. Straathof
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
| |
Collapse
|
24
|
Formation of alkenes via degradation of tert-alkyl ethers and alcohols by Aquincola tertiaricarbonis L108 and Methylibium spp. Appl Environ Microbiol 2011; 77:5981-7. [PMID: 21742915 DOI: 10.1128/aem.00093-11] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial degradation pathways of fuel oxygenates such as methyl tert-butyl and tert-amyl methyl ether (MTBE and TAME, respectively) have already been studied in some detail. However, many of the involved enzymes are still unknown, and possible side reactions have not yet been considered. In Aquincola tertiaricarbonis L108, Methylibium petroleiphilum PM1, and Methylibium sp. strain R8, we have now detected volatile hydrocarbons as by-products of the degradation of the tert-alkyl ether metabolites tert-butyl and tert-amyl alcohol (TBA and TAA, respectively). The alkene isobutene was formed only during TBA catabolism, while the beta and gamma isomers of isoamylene were produced only during TAA conversion. Both tert-alkyl alcohol degradation and alkene production were strictly oxygen dependent. However, the relative contribution of the dehydration reaction to total alcohol conversion increased with decreasing oxygen concentrations. In resting-cell experiments where the headspace oxygen content was adjusted to less than 2%, more than 50% of the TAA was converted to isoamylene. Isobutene formation from TBA was about 20-fold lower, reaching up to 4% alcohol turnover at low oxygen concentrations. It is likely that the putative tert-alkyl alcohol monooxygenase MdpJ, belonging to the Rieske nonheme mononuclear iron enzymes and found in all three strains tested, or an associated enzymatic step catalyzed the unusual elimination reaction. This was also supported by the detection of mdpJK genes in MTBE-degrading and isobutene-emitting enrichment cultures obtained from two treatment ponds operating at Leuna, Germany. The possible use of alkene formation as an easy-to-measure indicator of aerobic fuel oxygenate biodegradation in contaminated aquifers is discussed.
Collapse
|
25
|
Corynebacterium glutamicum tailored for efficient isobutanol production. Appl Environ Microbiol 2011; 77:3300-10. [PMID: 21441331 DOI: 10.1128/aem.02972-10] [Citation(s) in RCA: 215] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We recently engineered Corynebacterium glutamicum for aerobic production of 2-ketoisovalerate by inactivation of the pyruvate dehydrogenase complex, pyruvate:quinone oxidoreductase, transaminase B, and additional overexpression of the ilvBNCD genes, encoding acetohydroxyacid synthase, acetohydroxyacid isomeroreductase, and dihydroxyacid dehydratase. Based on this strain, we engineered C. glutamicum for the production of isobutanol from glucose under oxygen deprivation conditions by inactivation of l-lactate and malate dehydrogenases, implementation of ketoacid decarboxylase from Lactococcus lactis, alcohol dehydrogenase 2 (ADH2) from Saccharomyces cerevisiae, and expression of the pntAB transhydrogenase genes from Escherichia coli. The resulting strain produced isobutanol with a substrate-specific yield (Y(P/S)) of 0.60 ± 0.02 mol per mol of glucose. Interestingly, a chromosomally encoded alcohol dehydrogenase rather than the plasmid-encoded ADH2 from S. cerevisiae was involved in isobutanol formation with C. glutamicum, and overexpression of the corresponding adhA gene increased the Y(P/S) to 0.77 ± 0.01 mol of isobutanol per mol of glucose. Inactivation of the malic enzyme significantly reduced the Y(P/S), indicating that the metabolic cycle consisting of pyruvate and/or phosphoenolpyruvate carboxylase, malate dehydrogenase, and malic enzyme is responsible for the conversion of NADH + H+ to NADPH + H+. In fed-batch fermentations with an aerobic growth phase and an oxygen-depleted production phase, the most promising strain, C. glutamicum ΔaceE Δpqo ΔilvE ΔldhA Δmdh(pJC4ilvBNCD-pntAB)(pBB1kivd-adhA), produced about 175 mM isobutanol, with a volumetric productivity of 4.4 mM h⁻¹, and showed an overall Y(P/S) of about 0.48 mol per mol of glucose in the production phase.
Collapse
|