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Engineering of central carbon metabolism in recombinant Saccharomyces cerevisiae for improved production of biopolymers

Bjurman, Nina LU (2016) KMB820 20161
Applied Microbiology
Biotechnology
Abstract
Bioplastics are a promising alternative for petroleum-based plastics that today is on high demand in our contemporary lifestyles. They are made from biopolymers such as polyhydroxyalkanoates (PHAs). Producing biopolymers from waste material feedstock using microbes increases profitability and environmental benefits as well as sustainability for biorefineries. Saccharomyces cerevisiae is a robust microorganism that fits for this task. Engineered S. cerevisiae strains are already able to consume sugars present in the waste streams such as glucose and xylose, additionally also able to produce the biopolymer Poly-(R)-3-hydroxybutyrate (PHB) were in this study further engineered to improve yields, productivities and titers. In strategy one a... (More)
Bioplastics are a promising alternative for petroleum-based plastics that today is on high demand in our contemporary lifestyles. They are made from biopolymers such as polyhydroxyalkanoates (PHAs). Producing biopolymers from waste material feedstock using microbes increases profitability and environmental benefits as well as sustainability for biorefineries. Saccharomyces cerevisiae is a robust microorganism that fits for this task. Engineered S. cerevisiae strains are already able to consume sugars present in the waste streams such as glucose and xylose, additionally also able to produce the biopolymer Poly-(R)-3-hydroxybutyrate (PHB) were in this study further engineered to improve yields, productivities and titers. In strategy one a heterologous acetylating acetaldehyde dehydrogenase (eutE) originally from Escherichia coli, was codon optimized and introduced into S. cerevisisae. In strategy two, an acetyl-CoA synthase originally from Salmonella enterica (acsL461P) was also introduced in combination with upregulated homogenous acetaldehyde dehydrogenase (ALD6). As last engineering step, to further direct the carbon flux towards PHB, alcohol dehydrogenase 1 (ADH1) was disrupted. The results show that Δadh1 strains will direct the carbon flux best towards PHB compared to the other strains. Strains expressing eutE decreased all of their PHB production suggesting that the kinetics of the heterologous acetylating acetaldehyde dehydrogenase might not be favorable for the conditions present when using xylose as a carbon source. (Less)
Popular Abstract (Swedish)
En viktig komponent i vårt moderna samhälle är plaster och användandet av detta material ökar. Plaster skapas av komponenter som extraheras från petroleum, ett icke-förnybart fossilt bränsle. För en hållbar framtid måste användandet av petroleum minska. Alternativ till petroleum-baserade plaster är bio-plaster. Bioraffinaderier använder idag mindre än 20 % av biomassan för etanolproduktion, överskottet bränns för energiproduktion. Om detta avfall istället skulle kunna användas som substrat till mervärdeskomponenter såsom bioplaster skulle detta vara fördelaktigt.
Bioplaster består av biopolymerer som produceras i naturen och som efter användning naturligt kan brytas ner. Det finns många typer av naturligt producerade biopolymerer, t.ex... (More)
En viktig komponent i vårt moderna samhälle är plaster och användandet av detta material ökar. Plaster skapas av komponenter som extraheras från petroleum, ett icke-förnybart fossilt bränsle. För en hållbar framtid måste användandet av petroleum minska. Alternativ till petroleum-baserade plaster är bio-plaster. Bioraffinaderier använder idag mindre än 20 % av biomassan för etanolproduktion, överskottet bränns för energiproduktion. Om detta avfall istället skulle kunna användas som substrat till mervärdeskomponenter såsom bioplaster skulle detta vara fördelaktigt.
Bioplaster består av biopolymerer som produceras i naturen och som efter användning naturligt kan brytas ner. Det finns många typer av naturligt producerade biopolymerer, t.ex poly-3- D-hydroxybutyrate (PHB). PHB kan vara den mest lovande biopolymeren då den delar många fysikaliska egenskaper med polypropylen.
Bagerijästen Saccharomyces cerevisiae är en av de mest välstuderade mikroorganismerna som under årtionden har blivit använd för produktion av mervärdeskemikalier, såsom etanol. Dess robusthet i storskaliga processer gör den till en attraktiv värdorganism. Att den även kan växa på billiga media såsom restavfall från bioraffinaderier bidrar likaså till detta intresse. Stammar av S.cerevisiae, redan designade för att konsumera olika sockerarter som naturligt finns i restavfall, samtidigt som den producerar PHB, har i detta projekt blivit optimerad ytterligare med de nyaste teknikerna inom genetisk manipulering. Målet med projektet var att minska bildandet av biprodukter samtidigt som utbytet av PHB ökade. Genom att ta bort en väsentlig gen för etanolproduktion, som i detta fallet ses som en biprodukt, lyckades en jäststam skapas med bättre kapacitet på att producera PHB. (Less)
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author
Bjurman, Nina LU
supervisor
organization
alternative title
Manipulering av central-metabolismen i rekombinant Saccharomyces cerevisiae för förbättrad produktion av biopolymerer.
course
KMB820 20161
year
type
H2 - Master's Degree (Two Years)
subject
keywords
waste material, Saccharomyces cerevisiae, biopolymer, genetic manipulation, metabolic engineering, applied microbiology, teknisk mikrobiologi
language
English
id
8891516
date added to LUP
2016-09-30 08:36:46
date last changed
2016-11-30 04:09:56
@misc{8891516,
  abstract     = {Bioplastics are a promising alternative for petroleum-based plastics that today is on high demand in our contemporary lifestyles. They are made from biopolymers such as polyhydroxyalkanoates (PHAs). Producing biopolymers from waste material feedstock using microbes increases profitability and environmental benefits as well as sustainability for biorefineries. Saccharomyces cerevisiae is a robust microorganism that fits for this task. Engineered S. cerevisiae strains are already able to consume sugars present in the waste streams such as glucose and xylose, additionally also able to produce the biopolymer Poly-(R)-3-hydroxybutyrate (PHB) were in this study further engineered to improve yields, productivities and titers. In strategy one a heterologous acetylating acetaldehyde dehydrogenase (eutE) originally from Escherichia coli, was codon optimized and introduced into S. cerevisisae. In strategy two, an acetyl-CoA synthase originally from Salmonella enterica (acsL461P) was also introduced in combination with upregulated homogenous acetaldehyde dehydrogenase (ALD6). As last engineering step, to further direct the carbon flux towards PHB, alcohol dehydrogenase 1 (ADH1) was disrupted. The results show that Δadh1 strains will direct the carbon flux best towards PHB compared to the other strains. Strains expressing eutE decreased all of their PHB production suggesting that the kinetics of the heterologous acetylating acetaldehyde dehydrogenase might not be favorable for the conditions present when using xylose as a carbon source.},
  author       = {Bjurman, Nina},
  keyword      = {waste material,Saccharomyces cerevisiae,biopolymer,genetic manipulation,metabolic engineering,applied microbiology,teknisk mikrobiologi},
  language     = {eng},
  note         = {Student Paper},
  title        = {Engineering of central carbon metabolism in recombinant Saccharomyces cerevisiae for improved production of biopolymers},
  year         = {2016},
}