Genetic and nutrient modulation of acetyl-CoA levels in Synechocystis for n-butanol production
Journal article, 2015

Background: There is a strong interest in using photosynthetic cyanobacteria as production hosts for biofuels and chemicals. Recent work has shown the benefit of pathway engineering, enzyme tolerance, and co-factor usage for improving yields of fermentation products. Results: An n-butanol pathway was inserted into a Synechocystis mutant deficient in polyhydroxybutyrate synthesis. We found that nitrogen starvation increased specific butanol productivity up to threefold, but cessation of cell growth limited total n-butanol titers. Metabolite profiling showed that acetyl-CoA increased twofold during nitrogen starvation. Introduction of a phosphoketolase increased acetyl-CoA levels sixfold at nitrogen replete conditions and increased butanol titers from 22 to 37 mg/L at day 8. Flux balance analysis of photoautotrophic metabolism showed that a Calvin-Benson-Bassham-Phosphoketolase pathway had higher theoretical butanol productivity than CBB-Embden-Meyerhof-Parnas and a reduced butanol ATP demand. Conclusion: These results demonstrate that phosphoketolase overexpression and modulation of nitrogen levels are two attractive routes toward increased production of acetyl-CoA derived products in cyanobacteria and could be implemented with complementary metabolic engineering strategies.





Metabolic engineering



J. Anfelt

Royal Institute of Technology (KTH)

D. Kaczmarzyk

Royal Institute of Technology (KTH)

K. Shabestary

Royal Institute of Technology (KTH)

B. Renberg

Royal Institute of Technology (KTH)

J. Rockberg

Royal Institute of Technology (KTH)

Jens B Nielsen

Chalmers, Biology and Biological Engineering, Systems and Synthetic Biology

M. Uhlen

Technical University of Denmark (DTU)

Royal Institute of Technology (KTH)

E. P. Hudson

Royal Institute of Technology (KTH)

Microbial Cell Factories

1475-2859 (ISSN)

Vol. 14 1 12-

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Life Science Engineering (2010-2018)

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