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Biocatalyst Engineering: Metabolic Engineering, Kinetic modeling and metagenomics applied to industrial biotechnology

Skorupa Parachin, Nadia LU (2010)
Abstract
Industrial biotechnology has been defined as the use and application of

biotechnology for the sustainable processing and production of chemicals,

materials and fuels. It makes use of biocatalysts such as microbial communities,

whole-cell microorganisms or purified enzymes. Although biocatalysts are

considered advantageous, since they operate under mild conditions regarding

temperature and pH and enable chemo-, regio-, and stereoselective reactions,

their utilization on the industrial scale can be impeded by sub-optimal

performance. The present study was aimed at the improvement of two biocatalytic

processes: whole-cell bioreduction for the production of optically... (More)
Industrial biotechnology has been defined as the use and application of

biotechnology for the sustainable processing and production of chemicals,

materials and fuels. It makes use of biocatalysts such as microbial communities,

whole-cell microorganisms or purified enzymes. Although biocatalysts are

considered advantageous, since they operate under mild conditions regarding

temperature and pH and enable chemo-, regio-, and stereoselective reactions,

their utilization on the industrial scale can be impeded by sub-optimal

performance. The present study was aimed at the improvement of two biocatalytic

processes: whole-cell bioreduction for the production of optically pure

alcohols, and ethanol production from lignocellulosic feedstock.

The reduction of the bicyclic diketone, bicyclo[2.2.2]octane-2,6-dione into

1R,4S,6S-6-hydroxy-bicyclo[2.2.2]octane-2-one (endo-alcohol) and 1S,4R,6S-6-

hydroxy-bicyclo[2.2.2]octane-2-one (exo-alcohol) was used as a model bioreduction

reaction. The identification and overexpression of an exo-reductase

encoding gene in Candida tropicalis enabled the production of the uncommon

exo-alcohol as major product. In parallel, the advantages and disadvantages of

metabolically engineered Saccharomyces cerevisiae and Escherichia coli as host

for whole-cell bioreduction were compared for the production of the endoalcohol.

Both these microorganisms gave about the same product purity. While

E. coli showed a three times higher reduction rate, higher cell viability was

maintained during the bioreductions with recombinant S. cerevisiae, which

resulted in higher final conversion (95%) and indicated that yeast could be

recycled.

Improvement of bioethanol production from xylose was achieved through the

construction and use of a kinetic model as a simulation tool for metabolic

engineering of recombinant S. cerevisiae strains. In parallel, novel xylose

isomerases and reductases were isolated from soil metagenome libraries by

sequence- and activity-based screening methods. In addition a novel indirect

protocol for soil DNA extraction that enabled the isolation of environmental

DNA at high yield and purity was developed.

This study enabled the expansion of a biocatalyst toolbox by providing new

catalysts, screening methods and generating new recombinant strains with

improved properties, which can be utilized in the pharmaceutical and bioenergy

sectors, and thus constitutes a step forward in the development of novel biobased

processes. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Nevoigt, Elke, Jacobs University, Bremen, Germany
organization
publishing date
type
Thesis
publication status
published
subject
keywords
industrial biocatalysts, metagenomics, biocatalyst, Saccharomyces cerevisiae
pages
110 pages
defense location
Lecture hall B, Center of Chemistry and Chemical Engineering, Getingev├Ągen 60, Lund University Faculty of Engineering
defense date
2010-10-14 10:00
ISBN
978-91-7473-011-1
language
English
LU publication?
yes
id
d705c268-0be0-4751-b8f5-588d8c59fcc4 (old id 1680135)
date added to LUP
2010-09-21 15:10:34
date last changed
2016-09-19 08:45:16
@phdthesis{d705c268-0be0-4751-b8f5-588d8c59fcc4,
  abstract     = {Industrial biotechnology has been defined as the use and application of<br/><br>
biotechnology for the sustainable processing and production of chemicals,<br/><br>
materials and fuels. It makes use of biocatalysts such as microbial communities,<br/><br>
whole-cell microorganisms or purified enzymes. Although biocatalysts are<br/><br>
considered advantageous, since they operate under mild conditions regarding<br/><br>
temperature and pH and enable chemo-, regio-, and stereoselective reactions,<br/><br>
their utilization on the industrial scale can be impeded by sub-optimal<br/><br>
performance. The present study was aimed at the improvement of two biocatalytic<br/><br>
processes: whole-cell bioreduction for the production of optically pure<br/><br>
alcohols, and ethanol production from lignocellulosic feedstock.<br/><br>
The reduction of the bicyclic diketone, bicyclo[2.2.2]octane-2,6-dione into<br/><br>
1R,4S,6S-6-hydroxy-bicyclo[2.2.2]octane-2-one (endo-alcohol) and 1S,4R,6S-6-<br/><br>
hydroxy-bicyclo[2.2.2]octane-2-one (exo-alcohol) was used as a model bioreduction<br/><br>
reaction. The identification and overexpression of an exo-reductase<br/><br>
encoding gene in Candida tropicalis enabled the production of the uncommon<br/><br>
exo-alcohol as major product. In parallel, the advantages and disadvantages of<br/><br>
metabolically engineered Saccharomyces cerevisiae and Escherichia coli as host<br/><br>
for whole-cell bioreduction were compared for the production of the endoalcohol.<br/><br>
Both these microorganisms gave about the same product purity. While<br/><br>
E. coli showed a three times higher reduction rate, higher cell viability was<br/><br>
maintained during the bioreductions with recombinant S. cerevisiae, which<br/><br>
resulted in higher final conversion (95%) and indicated that yeast could be<br/><br>
recycled.<br/><br>
Improvement of bioethanol production from xylose was achieved through the<br/><br>
construction and use of a kinetic model as a simulation tool for metabolic<br/><br>
engineering of recombinant S. cerevisiae strains. In parallel, novel xylose<br/><br>
isomerases and reductases were isolated from soil metagenome libraries by<br/><br>
sequence- and activity-based screening methods. In addition a novel indirect<br/><br>
protocol for soil DNA extraction that enabled the isolation of environmental<br/><br>
DNA at high yield and purity was developed.<br/><br>
This study enabled the expansion of a biocatalyst toolbox by providing new<br/><br>
catalysts, screening methods and generating new recombinant strains with<br/><br>
improved properties, which can be utilized in the pharmaceutical and bioenergy<br/><br>
sectors, and thus constitutes a step forward in the development of novel biobased<br/><br>
processes.},
  author       = {Skorupa Parachin, Nadia},
  isbn         = {978-91-7473-011-1},
  keyword      = {industrial biocatalysts,metagenomics,biocatalyst,Saccharomyces cerevisiae},
  language     = {eng},
  pages        = {110},
  school       = {Lund University},
  title        = {Biocatalyst Engineering: Metabolic Engineering, Kinetic modeling and metagenomics applied to industrial biotechnology},
  year         = {2010},
}