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Development of a gas/liquid membrane contactor for oxygen delivery in enzymatic conversions

Wouter Van Hecke UGent (2009)
abstract
Manufacturing of fine chemicals traditionally involves oxidations with stoichiometric amounts of oxidants such as hypochlorite, bromine, permanganate, m-chloroperoxybenzoic acid, (trifluoro)peroxyacetic acid and others leading to large amounts of toxic effluents. In contrast, molecular oxygen is the most inexpensive and harmless oxidant availabe. Enzymatic activation of molecular oxygen is an interesting biotechnological reaction in the conversion of a wide range of substrates into their more valuable oxidized products. The promotion of the use of molecular oxygen as primary oxidant for sustainable oxidations in the fine chemical industry using isolated biocatalysts was the main motivation to start this work. Even though its great biocatalytic potential, stability and productivity still often limit the use of these biocatalysts. In this dissertation, the primary objective was to study bubbleless oxygenation with membranes as a method for the prevention of gas/liquid inactivation of isolated enzymes. This was experimentally studied on a small scale (200 mL) for the conversion of lactose to lactobionic acid using cellobiose dehydrogenase as the synthesizing enzyme and a laccase-mediator system for regeneration of the flavo-enzyme. Kinetic modeling of the enzymatic conversion of lactose to lactobionic acid lead to a thorough understanding of the seemingly complicated reactions and provided a framework for rationalization of biocatalyst and redox mediator use. A similar approach was used to quantitatively describe the interactions between a laccase-mediator system and pyranose 2-oxidase for production of 2-ketoaldoses. Reaction engineering enabled to shift the pathway from oxygen to redox mediator reduction by pyranose 2-oxidase and thus lead to an increased productivity and stability of the system without the addition of catalase. The experimental knowledge gathered during the conversions on small scale and the developed kinetic model for conversion of lactose to lactobionic acid made us confident enough to upscale this conversion to 20 L using the dynamic membrane aeration reactor originally developed for aeration of sensitive animal cells by Bayer Technology Services. This reactor was both operated in batch and continuous mode. Ultrafiltration membranes were used in the continuous mode to retain the biocatalysts in the reactor. Some aspects that were studied in this dissertation require further elaboration and optimization, but it is clear that the concept of bubbleless oxygenation can be beneficial for a number of biocatalytic oxidations and we are convinced that the developed reaction engineering approach will become a versatile tool for optimization and upscaling of biocatalytic oxidations based on isolated enzymes with enzymatic redox mediator/coenzyme regeneration.
Please use this url to cite or link to this publication:
author
promoter
UGent and UGent
organization
alternative title
Ontwikkeling van een gas/vloeistof membraancontactor voor zuurstofvoorziening in enzymatische conversies
year
type
dissertation (monograph)
subject
keyword
redox mediator regeneration, laccase, biocatalytic cascade oxidations, membrane contactor, kinetic modeling, flavo-enzyme
pages
VI, 128 pages
publisher
Ghent University. Faculty of Bioscience Engineering
place of publication
Ghent, Belgium
defense location
Gent : Het Pand (Priorzaal)
defense date
2009-11-06 18:00
ISBN
978-90-5989-325-2
language
English
UGent publication?
yes
classification
D1
copyright statement
I have retained and own the full copyright for this publication
id
764646
handle
http://hdl.handle.net/1854/LU-764646
alternative location
http://lib.ugent.be/fulltxt/RUG01/001/362/827/RUG01-001362827_2010_0001_AC.pdf
date created
2009-10-17 17:33:14
date last changed
2009-10-21 14:03:17
@phdthesis{764646,
  abstract     = {Manufacturing of fine chemicals traditionally involves oxidations with stoichiometric amounts of oxidants such as hypochlorite, bromine, permanganate, m-chloroperoxybenzoic acid, (trifluoro)peroxyacetic acid and others leading to large amounts of toxic effluents. In contrast, molecular oxygen is the most inexpensive and harmless oxidant availabe. Enzymatic activation of molecular oxygen is an interesting biotechnological reaction in the conversion of a wide range of substrates into their more valuable oxidized products. 
The promotion of the use of molecular oxygen as primary oxidant for sustainable oxidations in the fine chemical industry using isolated biocatalysts was the main motivation to start this work. Even though its great biocatalytic potential, stability and productivity still often limit the use of these biocatalysts. In this dissertation, the primary objective was to study bubbleless oxygenation with membranes as a method for the prevention of gas/liquid inactivation of isolated enzymes. This was experimentally studied on a small scale (200 mL) for the conversion of lactose to lactobionic acid using cellobiose dehydrogenase as the synthesizing enzyme and a laccase-mediator system for regeneration of the flavo-enzyme. 
Kinetic modeling of the enzymatic conversion of lactose to lactobionic acid lead to a thorough understanding of the seemingly complicated reactions and provided a framework for rationalization of biocatalyst and redox mediator use.  
A similar approach was used to quantitatively describe the interactions between a laccase-mediator system and pyranose 2-oxidase for production of 2-ketoaldoses. Reaction engineering enabled to shift the pathway from oxygen to redox mediator reduction by pyranose 2-oxidase and thus lead to an increased productivity and stability of the system without the addition of catalase. 
The experimental knowledge gathered during the conversions on small scale and the developed kinetic model for conversion of lactose to lactobionic acid made us confident enough to upscale this conversion to 20 L using the dynamic membrane aeration reactor originally developed for aeration of sensitive animal cells by Bayer Technology Services. This reactor was both operated in batch and continuous mode. Ultrafiltration membranes were used in the continuous mode to retain the biocatalysts in the reactor.
Some aspects that were studied in this dissertation require further elaboration and optimization, but it is clear that the concept of bubbleless oxygenation can be beneficial for a number of biocatalytic oxidations and we are convinced that the developed reaction engineering approach will become a versatile tool for optimization and upscaling of biocatalytic oxidations based on isolated enzymes with enzymatic redox mediator/coenzyme regeneration.},
  author       = {Van Hecke, Wouter},
  isbn         = {978-90-5989-325-2},
  keyword      = {redox mediator regeneration,laccase,biocatalytic cascade oxidations,membrane contactor,kinetic modeling,flavo-enzyme},
  language     = {eng},
  pages        = {VI, 128},
  publisher    = {Ghent University. Faculty of Bioscience Engineering},
  school       = {Ghent University},
  title        = {Development of a gas/liquid membrane contactor for oxygen delivery in enzymatic conversions},
  url          = {http://lib.ugent.be/fulltxt/RUG01/001/362/827/RUG01-001362827\_2010\_0001\_AC.pdf},
  year         = {2009},
}

Chicago
Van Hecke, Wouter. 2009. “Development of a Gas/liquid Membrane Contactor for Oxygen Delivery in Enzymatic Conversions”. Ghent, Belgium: Ghent University. Faculty of Bioscience Engineering.
APA
Van Hecke, W. (2009). Development of a gas/liquid membrane contactor for oxygen delivery in enzymatic conversions. Ghent University. Faculty of Bioscience Engineering, Ghent, Belgium.
Vancouver
1.
Van Hecke W. Development of a gas/liquid membrane contactor for oxygen delivery in enzymatic conversions. [Ghent, Belgium]: Ghent University. Faculty of Bioscience Engineering; 2009.
MLA
Van Hecke, Wouter. “Development of a Gas/liquid Membrane Contactor for Oxygen Delivery in Enzymatic Conversions.” 2009 : n. pag. Print.