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3. Prozessintensivierung der Gasfermentation mit Acetobacterium woodii in Rührkesselreaktoren

Author

Liebl, Wolfgang (Prof. Dr.), Weuster-Botz, Dirk (Prof. Dr.), Kantzow, Christina, Liebl, Wolfgang (Prof. Dr.), Weuster-Botz, Dirk (Prof. Dr.), and Kantzow, Christina

Abstract

Eine Alternative zur Synthese von Essigsäure aus fossilen Rohstoffen sind Gasfermentationen, bei denen Kohlenstoffdioxid mit Wasserstoff durch acetogene Bakterien zu Acetat umgesetzt wird. Die reaktionstechnische Analyse von Gasfermentationen mit A. woodii im Rührkesselreaktor zeigte, dass hohe Acetatkonzentrationen (60 g/L) im einfachen Satzverfahren und hohe Raum-Zeit-Ausbeuten (148 g/L/d) im kontinuierlich betriebenen Membranreaktor bei vollständiger Zellrückhaltung erreicht werden können., Gas fermentations using acetogenic bacteria to convert carbon dioxide with hydrogen into acetate represent an alternative to the synthesis of acetic acid from fossil resources. Reaction engineering analysis of gas fermentations with A. woodii resulted in high acetate concentrations (60 g/L) in batch operated stirred-tank bioreactors. High space time yields (148 g/L/d) were achieved in continuously operated membrane bioreactors with full cell retention.

Published
2016

4. Prozessintensivierung der Gasfermentation mit Acetobacterium woodii in Rührkesselreaktoren

Author

Weuster-Botz, Dirk (Prof. Dr.), Weuster-Botz, Dirk (Prof. Dr.);Liebl, Wolfgang (Prof. Dr.), Kantzow, Christina, Weuster-Botz, Dirk (Prof. Dr.), Weuster-Botz, Dirk (Prof. Dr.);Liebl, Wolfgang (Prof. Dr.), and Kantzow, Christina

Abstract

Eine Alternative zur Synthese von Essigsäure aus fossilen Rohstoffen sind Gasfermentationen, bei denen Kohlenstoffdioxid mit Wasserstoff durch acetogene Bakterien zu Acetat umgesetzt wird. Die reaktionstechnische Analyse von Gasfermentationen mit A. woodii im Rührkesselreaktor zeigte, dass hohe Acetatkonzentrationen (60 g/L) im einfachen Satzverfahren und hohe Raum-Zeit-Ausbeuten (148 g/L/d) im kontinuierlich betriebenen Membranreaktor bei vollständiger Zellrückhaltung erreicht werden können., Gas fermentations using acetogenic bacteria to convert carbon dioxide with hydrogen into acetate represent an alternative to the synthesis of acetic acid from fossil resources. Reaction engineering analysis of gas fermentations with A. woodii resulted in high acetate concentrations (60 g/L) in batch operated stirred-tank bioreactors. High space time yields (148 g/L/d) were achieved in continuously operated membrane bioreactors with full cell retention.

Published
2016

6. Multi-enzymatic one-pot reduction of dehydrocholic acid to 12-keto-ursodeoxycholic acid with whole-cell biocatalysts.

Author

Sun, Boqiao, Kantzow, Christina, Bresch, SvEN, Castiglione, Kathrin, and Weuster ‐ Botz, Dirk

Abstract

Ursodeoxycholic acid (UDCA) is a bile acid of industrial interest as it is used as an agent for the treatment of primary sclerosing cholangitis and the medicamentous, non-surgical dissolution of gallstones. Currently, it is prepared industrially from cholic acid following a seven-step chemical procedure with an overall yield of <30%. In this study, we investigated the key enzymatic steps in the chemo-enzymatic preparation of UDCA-the two-step reduction of dehydrocholic acid (DHCA) to 12-keto-ursodeoxycholic acid using a mutant of 7β-hydroxysteroid dehydrogenase (7β-HSDH) from Collinsella aerofaciens and 3α-hydroxysteroid dehydrogenase (3α-HSDH) from Comamonas testosteroni. Three different one-pot reaction approaches were investigated using whole-cell biocatalysts in simple batch processes. We applied one-biocatalyst systems, where 3α-HSDH, 7β-HSDH, and either a mutant of formate dehydrogenase (FDH) from Mycobacterium vaccae N10 or a glucose dehydrogenase (GDH) from Bacillus subtilis were expressed in a Escherichia coli BL21(DE3) based host strain. We also investigated two-biocatalyst systems, where 3α-HSDH and 7β-HSDH were expressed separately together with FDH enzymes for cofactor regeneration in two distinct E. coli hosts that were simultaneously applied in the one-pot reaction. The best result was achieved by the one-biocatalyst system with GDH for cofactor regeneration, which was able to completely convert 100 mM DHCA to >99.5 mM 12-keto-UDCA within 4.5 h in a simple batch process on a liter scale. Biotechnol. Bioeng. 2013; 110: 68-77. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Published
2013
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