This title appears in the Scientific Report :
2014
Please use the identifier:
http://hdl.handle.net/2128/8532 in citations.
Engineering of Corynebacterium glutamicum towards utilization of Methanol as carbon and energy source
Engineering of Corynebacterium glutamicum towards utilization of Methanol as carbon and energy source
Methanol is a pure and inexpensive raw material, which is mainly produced from fossil-fuel-based synthesis gas. Over the past years, new approaches were developed for its production from renewable carbon sources. In the chemical industry, methanol is already an important carbon feedstock, but it has...
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Personal Name(s): | Witthoff, Sabrina (Corresponding Author) |
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Contributing Institute: |
Biotechnologie; IBG-1 |
Published in: | 2015 |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2015
|
Physical Description: |
V, 113 S. |
Dissertation Note: |
Universität Düsseldorf, Diss., 2014 |
ISBN: |
978-3-95806-029-6 |
Document Type: |
Book Dissertation / PhD Thesis |
Research Program: |
Addenda |
Series Title: |
Schriften des Forschungszentrums Jülich. Reihe Gesundheit / Health
78 |
Subject (ZB): | |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
Methanol is a pure and inexpensive raw material, which is mainly produced from fossil-fuel-based synthesis gas. Over the past years, new approaches were developed for its production from renewable carbon sources. In the chemical industry, methanol is already an important carbon feedstock, but it has found only limited application in biotechnology. This can predominantly be attributed to the inability of important microbial platform organisms to utilize this C$_{1}$ compound. With the aim to make methanol a suitable substrate for microbial production processes, the non-methylotrophic and industrially important amino acid-producing bacterium $\textit{Corynebacterium glutamicum}$ was engineered towards the utilization of methanol as auxiliary carbon source in a sugar-based medium. Initial experiments on the response of $\textit{C. glutamicum}$ to methanol showed that this organismis able to oxidize methanol to CO$_{2}$ during the stationary phase with a rate of 0.83 ± 0.2 mM/h(2.8 ± 0.5 nmol min$^{-1}$ mg CDW$^{-1}$) in glucose/methanol defined medium. Methanol oxidation was shown to be subject to carbon catabolite repression in the presence of glucose and to be dependent on the transcriptional regulator RamA. Global gene expression studies revealed that the alcohol dehydrogenase gene $\textit{adhA}$ as well as the aldehyde dehydrogenase gene $\textit{ald}$ were upregulated in the presence of methanol. Analysis of a mutant lacking the $\textit{adhA}$ gene showed a67% reduced methanol consumption rate (0.27 ± 0.05 mM/h), indicating that AdhA is mainly responsible for the oxidation of methanol to formaldehyde. The oxidation of formaldehyde to formate was found to be catalyzed predominantly by two enzymes, the acetaldehyde dehydrogenase Ald and the mycothiol-dependent formaldehyde dehydrogenase AdhE. A double mutant lacking $\textit{ald}$ and $\textit{adhE}$ was severely impaired in its ability to oxidize formaldehyde. The oxidation of formate to CO$_{2}$ is catalyzed by formate dehydrogenase (FDH). Deletion of $\textit{fdhF}$ (annotated as FDH) and $\textit{fdhD}$ (annotated as FDH accessory protein) in $\textit{C. glutamicum}$ abolished formate oxidation and resulted in an increased formate sensitivity. Growth studies with molybdenum and tungsten indicated that FdhF is a molybdenum-dependent enzyme. The electron acceptor of FdhF is not NAD(P)$^{+}$ and still unknown. [...] |