Metabolic engineering of Synechocystis sp. Strain PCC 6803 for isobutanol production

Arul Varman, Yi Xiao, Himadri B. Pakrasi, Yinjie J. Tang

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

Global warming and decreasing fossil fuel reserves have prompted great interest in the synthesis of advanced biofuels from renewable resources. In an effort to address these concerns, we performed metabolic engineering of the cyanobacterium Synechocystis sp. strain PCC 6803 to develop a strain that can synthesize isobutanol under both autotrophic and mixotrophic conditions. With the expression of two heterologous genes from the Ehrlich pathway, the engineered strain can accumulate 90 mg/ liter of isobutanol from 50mMbicarbonate in a gas-tight shaking flask. The strain does not require any inducer (i.e., isopropyl β-D-1-thiogalactopyranoside [IPTG]) or antibiotics to maintain its isobutanol production. In the presence of glucose, isobutanol synthesis is only moderately promoted (titer=114 mg/liter). Based on isotopomer analysis, we found that, compared to the wild-type strain, the mutant significantly reduced its glucose utilization and mainly employed autotrophic metabolism for biomass growth and isobutanol production. Since isobutanol is toxic to the cells and may also be degraded photochemically by hydroxyl radicals during the cultivation process, we employed in situ removal of the isobutanol using oleyl alcohol as a solvent trap. This resulted in a final net concentration of 298 mg/liter of isobutanol under mixotrophic culture conditions.

Original languageEnglish (US)
Pages (from-to)908-914
Number of pages7
JournalApplied and Environmental Microbiology
Volume79
Issue number3
DOIs
StatePublished - Feb 1 2013
Externally publishedYes

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Synechocystis
Metabolic Engineering
metabolic engineering
glucose
engineering
renewable resource
hydroxyl radical
biofuel
antibiotics
fossil fuel
cyanobacterium
alcohol
global warming
metabolism
gene
biomass
renewable resources
gas
synthesis
fossil fuels

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

Cite this

Metabolic engineering of Synechocystis sp. Strain PCC 6803 for isobutanol production. / Varman, Arul; Xiao, Yi; Pakrasi, Himadri B.; Tang, Yinjie J.

In: Applied and Environmental Microbiology, Vol. 79, No. 3, 01.02.2013, p. 908-914.

Research output: Contribution to journalArticle

Varman, Arul ; Xiao, Yi ; Pakrasi, Himadri B. ; Tang, Yinjie J. / Metabolic engineering of Synechocystis sp. Strain PCC 6803 for isobutanol production. In: Applied and Environmental Microbiology. 2013 ; Vol. 79, No. 3. pp. 908-914.
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