Endre søk
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Using Transcriptomics To Improve Butanol Tolerance of Synechocystis sp Strain PCC 6803
KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi.ORCID-id: 0000-0002-2430-2682
KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi.ORCID-id: 0000-0001-8993-048X
Vise andre og tillknytning
2013 (engelsk)Inngår i: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 79, nr 23, s. 7419-7427Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Cyanobacteria are emerging as promising hosts for production of advanced biofuels such as n-butanol and alkanes. However, cyanobacteria suffer from the same product inhibition problems as those that plague other microbial biofuel hosts. High concentrations of butanol severely reduce growth, and even small amounts can negatively affect metabolic processes. An understanding of how cyanobacteria are affected by their biofuel product can enable identification of engineering strategies for improving their tolerance. Here we used transcriptome sequencing (RNA-Seq) to assess the transcriptome response of Synechocystis sp. strain PCC 6803 to two concentrations of exogenous n-butanol. Approximately 80 transcripts were differentially expressed at 40 mg/liter butanol, and 280 transcripts were different at 1 g/liter butanol. Our results suggest a compromised cell membrane, impaired photosynthetic electron transport, and reduced biosynthesis. Accumulation of intracellular reactive oxygen species (ROS) scaled with butanol concentration. Using the physiology and transcriptomics data, we selected several genes for overexpression in an attempt to improve butanol tolerance. We found that overexpression of several proteins, notably, the small heat shock protein HspA, improved tolerance to butanol. Transcriptomics-guided engineering created more solvent-tolerant cyanobacteria strains that could be the foundation for a more productive biofuel host.

sted, utgiver, år, opplag, sider
2013. Vol. 79, nr 23, s. 7419-7427
Emneord [en]
Advanced biofuels, Metabolic process, Photosynthetic electron transport, Product inhibition, Reactive oxygen species, Small heat shock proteins, Solvent-tolerant, Transcriptome response
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-139282DOI: 10.1128/AEM.02694-13ISI: 000327544700035Scopus ID: 2-s2.0-84888217221OAI: oai:DiVA.org:kth-139282DiVA, id: diva2:684634
Forskningsfinansiär
Formas
Merknad

QC 20140108

Tilgjengelig fra: 2014-01-08 Laget: 2014-01-08 Sist oppdatert: 2017-12-06bibliografisk kontrollert
Inngår i avhandling
1. Metabolic engineering strategies to increase n-butanol production from cyanobacteria
Åpne denne publikasjonen i ny fane eller vindu >>Metabolic engineering strategies to increase n-butanol production from cyanobacteria
2016 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The development of sustainable replacements for fossil fuels has been spurred by concerns over global warming effects. Biofuels are typically produced through fermentation of edible crops, or forest or agricultural residues requiring cost-intensive pretreatment. An alternative is to use photosynthetic cyanobacteria to directly convert CO2 and sunlight into fuel. In this thesis, the cyanobacterium Synechocystis sp. PCC 6803 was genetically engineered to produce the biofuel n­-butanol. Several metabolic engineering strategies were explored with the aim to increase butanol titers and tolerance.

In papers I-II, different driving forces for n-butanol production were evaluated. Expression of a phosphoketolase increased acetyl-CoA levels and subsequently butanol titers. Attempts to increase the NADH pool further improved titers to 100 mg/L in four days.

In paper III, enzymes were co-localized onto a scaffold to aid intermediate channeling. The scaffold was tested on a farnesene and polyhydroxybutyrate (PHB) pathway in yeast and in E. coli, respectively, and could be extended to cyanobacteria. Enzyme co-localization increased farnesene titers by 120%. Additionally, fusion of scaffold-recognizing proteins to the enzymes improved farnesene and PHB production by 20% and 300%, respectively, even in the absence of scaffold.

In paper IV, the gene repression technology CRISPRi was implemented in Synechocystis to enable parallel repression of multiple genes. CRISPRi allowed 50-95% repression of four genes simultaneously. The method will be valuable for repression of competing pathways to butanol synthesis.

Butanol becomes toxic at high concentrations, impeding growth and thus limiting titers. In papers V-VI, butanol tolerance was increased by overexpressing a heat shock protein or a stress-related sigma factor.

Taken together, this thesis demonstrates several strategies to improve butanol production from cyanobacteria. The strategies could ultimately be combined to increase titers further.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2016. s. 79
Serie
TRITA-BIO-Report, ISSN 1654-2312 ; 2016:4
Emneord
cyanobacteria, metabolic engineering, biofuels, butanol, synthetic scaffold, CRISPRi, solvent tolerance
HSV kategori
Forskningsprogram
Bioteknologi
Identifikatorer
urn:nbn:se:kth:diva-185548 (URN)978-91-7595-927-6 (ISBN)
Disputas
2016-05-27, FD5, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (engelsk)
Opponent
Veileder
Forskningsfinansiär
Swedish Research Council FormasKnut and Alice Wallenberg FoundationSwedish Foundation for Strategic Research
Tilgjengelig fra: 2016-04-22 Laget: 2016-04-21 Sist oppdatert: 2016-04-28bibliografisk kontrollert

Open Access i DiVA

Fulltekst mangler i DiVA

Andre lenker

Forlagets fulltekstScopus

Personposter BETA

Anfelt, JosefineUhlén, MathiasHudson, Elton Paul

Søk i DiVA

Av forfatter/redaktør
Anfelt, JosefineUhlén, MathiasHudson, Elton Paul
Av organisasjonen
I samme tidsskrift
Applied and Environmental Microbiology

Søk utenfor DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric

doi
urn-nbn
Totalt: 250 treff
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf