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White BE, Fenner CJ, Smit MS, Harrison STL. Effect of cell permeability and dehydrogenase expression on octane activation by CYP153A6-based whole cell Escherichia coli catalysts. Microb Cell Fact 2017; 16:156. [PMID: 28931395 PMCID: PMC5607502 DOI: 10.1186/s12934-017-0763-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Accepted: 09/07/2017] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The regeneration of cofactors and the supply of alkane substrate are key considerations for the biocatalytic activation of hydrocarbons by cytochrome P450s. This study focused on the biotransformation of n-octane to 1-octanol using resting Escherichia coli cells expressing the CYP153A6 operon, which includes the electron transport proteins ferredoxin and ferredoxin reductase. Glycerol dehydrogenase was co-expressed with the CYP153A6 operon to investigate the effects of boosting cofactor regeneration. In order to overcome the alkane supply bottleneck, various chemical and physical approaches to membrane permeabilisation were tested in strains with or without additional dehydrogenase expression. RESULTS Dehydrogenase co-expression in whole cells did not improve product formation and reduced the stability of the system at high cell densities. Chemical permeabilisation resulted in initial hydroxylation rates that were up to two times higher than the whole cell system, but severely impacted biocatalyst stability. Mechanical cell breakage led to improved enzyme stability, but additional dehydrogenase expression was necessary to improve product formation. The best-performing system (in terms of final titres) consisted of mechanically ruptured cells expressing additional dehydrogenase. This system had an initial activity of 1.67 ± 0.12 U/gDCW (32% improvement on whole cells) and attained a product concentration of 34.8 ± 1.6 mM after 24 h (22% improvement on whole cells). Furthermore, the system was able to maintain activity when biotransformation was extended to 72 h, resulting in a final product titre of 60.9 ± 1.1 mM. CONCLUSIONS This study suggests that CYP153A6 in whole cells is limited by coupling efficiencies rather than cofactor supply. However, the most significant limitation in the current system is hydrocarbon transport, with substrate import being the main determinant of hydroxylation rates, and product export playing a key role in system stability.
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Affiliation(s)
- Bronwyn E White
- Centre for Bioprocess Engineering Research (CeBER), Department of Chemical Engineering, University of Cape Town, Private Bag X3, Rondebosch, Cape Town, 7701, South Africa.,South African DST-NRF Centre of Excellence in Catalysis, c*change, University of Cape Town, Private Bag, Rondebosch, Cape Town, 7701, South Africa
| | - Caryn J Fenner
- Centre for Bioprocess Engineering Research (CeBER), Department of Chemical Engineering, University of Cape Town, Private Bag X3, Rondebosch, Cape Town, 7701, South Africa.,South African DST-NRF Centre of Excellence in Catalysis, c*change, University of Cape Town, Private Bag, Rondebosch, Cape Town, 7701, South Africa
| | - Martha S Smit
- Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, Bloemfontein, South Africa.,South African DST-NRF Centre of Excellence in Catalysis, c*change, University of Cape Town, Private Bag, Rondebosch, Cape Town, 7701, South Africa
| | - Susan T L Harrison
- Centre for Bioprocess Engineering Research (CeBER), Department of Chemical Engineering, University of Cape Town, Private Bag X3, Rondebosch, Cape Town, 7701, South Africa. .,South African DST-NRF Centre of Excellence in Catalysis, c*change, University of Cape Town, Private Bag, Rondebosch, Cape Town, 7701, South Africa.
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Holtmann D, Hollmann F. The Oxygen Dilemma: A Severe Challenge for the Application of Monooxygenases? Chembiochem 2016; 17:1391-8. [PMID: 27194219 PMCID: PMC5096067 DOI: 10.1002/cbic.201600176] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Indexed: 12/12/2022]
Abstract
Monooxygenases are promising catalysts because they in principle enable the organic chemist to perform highly selective oxyfunctionalisation reactions that are otherwise difficult to achieve. For this, monooxygenases require reducing equivalents, to allow reductive activation of molecular oxygen at the enzymes' active sites. However, these reducing equivalents are often delivered to O2 either directly or via a reduced intermediate (uncoupling), yielding hazardous reactive oxygen species and wasting valuable reducing equivalents. The oxygen dilemma arises from monooxygenases' dependency on O2 and the undesired uncoupling reaction. With this contribution we hope to generate a general awareness of the oxygen dilemma and to discuss its nature and some promising solutions.
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Affiliation(s)
- Dirk Holtmann
- DECHEMA Research Institute, Theodor-Heuss-Allee 25, 60486, Frankfurt am Main, Germany
| | - Frank Hollmann
- Department of Biotechnology, Delft University of Technology, Julianalaan 136, 2628BL, Delft, The Netherlands.
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Holtmann D, Fraaije MW, Arends IWCE, Opperman DJ, Hollmann F. The taming of oxygen: biocatalytic oxyfunctionalisations. Chem Commun (Camb) 2015; 50:13180-200. [PMID: 24902635 DOI: 10.1039/c3cc49747j] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The scope and limitations of oxygenases as catalysts for preparative organic synthesis is discussed.
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Affiliation(s)
- Dirk Holtmann
- DECHEMA Research Institute, Theodor-Heuss-Allee 25, 60486 Frankfurt am Main, Germany
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The substrate binding cavity of particulate methane monooxygenase from Methylosinus trichosporium OB3b expresses high enantioselectivity for n-butane and n-pentane oxidation to 2-alcohol. Biotechnol Lett 2011; 33:2241-6. [DOI: 10.1007/s10529-011-0688-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 07/01/2011] [Indexed: 11/26/2022]
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Seifert A, Antonovici M, Hauer B, Pleiss J. An Efficient Route to Selective Bio-oxidation Catalysts: an Iterative Approach Comprising Modeling, Diversification, and Screening, Based on CYP102A1. Chembiochem 2011; 12:1346-51. [DOI: 10.1002/cbic.201100067] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Indexed: 11/10/2022]
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Bordeaux M, Galarneau A, Fajula F, Drone J. A Regioselective Biocatalyst for Alkane Activation under Mild Conditions. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201005597] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Bordeaux M, Galarneau A, Fajula F, Drone J. A regioselective biocatalyst for alkane activation under mild conditions. Angew Chem Int Ed Engl 2011; 50:2075-9. [PMID: 21344555 DOI: 10.1002/anie.201005597] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 12/20/2010] [Indexed: 11/12/2022]
Affiliation(s)
- Mélanie Bordeaux
- Institut Charles Gerhardt Montpellier, UMR 5253 CNRS/ENSCM/UM2/UM1, 8, rue de l'Ecole Normale, 34296 Montpellier Cedex 5, France
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O'Reilly E, Köhler V, Flitsch SL, Turner NJ. Cytochromes P450 as useful biocatalysts: addressing the limitations. Chem Commun (Camb) 2011; 47:2490-501. [DOI: 10.1039/c0cc03165h] [Citation(s) in RCA: 199] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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van Beilen JB, Funhoff EG. Alkane hydroxylases involved in microbial alkane degradation. Appl Microbiol Biotechnol 2007; 74:13-21. [PMID: 17216462 DOI: 10.1007/s00253-006-0748-0] [Citation(s) in RCA: 300] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 11/03/2006] [Accepted: 11/05/2006] [Indexed: 11/30/2022]
Abstract
This review focuses on the role and distribution in the environment of alkane hydroxylases and their (potential) applications in bioremediation and biocatalysis. Alkane hydroxylases play an important role in the microbial degradation of oil, chlorinated hydrocarbons, fuel additives, and many other compounds. Environmental studies demonstrate the abundance of alkane degraders and have lead to the identification of many new species, including some that are (near)-obligate alkanotrophs. The availability of a growing collection of alkane hydroxylase gene sequences now allows estimations of the relative abundance of the different enzyme systems and the distribution of the host organisms.
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Affiliation(s)
- Jan B van Beilen
- Département de Biologie Moléculaire Végétale, Le Biophore, Quartier Sorge, Université de Lausanne, 1015, Lausanne, Switzerland.
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