This title appears in the Scientific Report :
2010
Please use the identifier:
http://hdl.handle.net/2128/15189 in citations.
Prozessentwicklung zur Produktion von 2-Keto-l-Glulonsäure, einer Vitamin C-Vorstufe
Prozessentwicklung zur Produktion von 2-Keto-l-Glulonsäure, einer Vitamin C-Vorstufe
In this study a process for the continuous production of 2-keto-L-gulonic acid was developed. This compound is a precursor of vitamin C and therefore of great industrial interest. 2-Keto-L-gulonic acid (2-KLG) was produced from D-glucose in a two-step reaction: Glucose was first oxidized to 2,5-dike...
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Personal Name(s): | Osterath, Brigitte (Corresponding author) |
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Contributing Institute: |
Biotechnologie 2; IBT-2 |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2010
|
Physical Description: |
XXI, 213 S. |
Dissertation Note: |
Universität Bonn, Diss., 2010 |
ISBN: |
978-3-89336-612-5 |
Document Type: |
Book Dissertation / PhD Thesis |
Research Program: |
Biotechnologie |
Series Title: |
Schriften des Forschungszentrums Jülich. Reihe Gesundheit / Health
22 |
Subject (ZB): | |
Link: |
OpenAccess |
Publikationsportal JuSER |
In this study a process for the continuous production of 2-keto-L-gulonic acid was developed. This compound is a precursor of vitamin C and therefore of great industrial interest. 2-Keto-L-gulonic acid (2-KLG) was produced from D-glucose in a two-step reaction: Glucose was first oxidized to 2,5-diketo-D-gluconic acid (2,5-DKG) with cells of $\textit{Gluconobacter oxydans}$, 2,5-DKG was then reduced to 2-KLG with the enzyme 2,5-diketo-D-gluconate reductase. Both reactions were carried out in separate reactors; 2,5-DKG was transferred into the second reactor without any further processing or purification. Resting cells of $\textit{Gluconobacter oxydans}$ could successfully be applied in batch and continuously stirred tank reactors (CSTR) for the production of 2,5-DKG. In both cases, sufficient supply of oxygen is crucial; in a specially constructed batch reactor the activity of the cells was increased threefold compared to the activity in shaking flasks. Thus, yields of up to 97% were achieved in the batch reactor. In a CSTR, yields of about 80% could be kept for several days, in that case the space-time-yield was 92 g$^{*}$L$^{-1}$d$^{-1}$. The enzyme 2,5-diketo-D-gluconate reductase (2,5-DKGR) was isolated and purified from recombinant $\textit{E. coli}$ cells in good yields of 0.31 mg$_{Protein/gcells}$. In kinetic investigations it accepted NADH as a cofactor but showed a much higher preference for NADPH (K$_{M, NADH}$ = 500 · K$_{M, NADPH}$). Cofactor regeneration worked best with the alcohol dehydrogenase from $\textit{Lactobacillus brevis}$. The two enzymes were successfully applied in an enzyme membrane reactor to produce 2-KLG from 2,5-DKG with yields of up to 100%. The highest space-time-yield was 329 g$^{*}$L$^{-1*}$d$^{-1}$ with product yields of 81%. After coupling the two reactor systems, 2-KLG could be produced continuously from D-glucose with yields of 68% and space-time-yields of 41.5 g$^{*}$L$^{-1*}$d$^{-1}$ for more than eight days. This study showed that the yields in this two-step reaction can be improved if the two steps are carried out in separate reactors. This way, the best reaction conditions for both oxidation and reduction can be adjusted. |