Genetic and nutrient modulation of acetyl-CoA levels in Synechocystis for n-butanol production
Artikel i vetenskaplig tidskrift, 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

Kungliga Tekniska Högskolan (KTH)

D. Kaczmarzyk

Kungliga Tekniska Högskolan (KTH)

K. Shabestary

Kungliga Tekniska Högskolan (KTH)

B. Renberg

Kungliga Tekniska Högskolan (KTH)

J. Rockberg

Kungliga Tekniska Högskolan (KTH)

Jens B Nielsen

Chalmers, Biologi och bioteknik, Systembiologi

M. Uhlen

Danmarks Tekniske Universitet (DTU)

Kungliga Tekniska Högskolan (KTH)

E. P. Hudson

Kungliga Tekniska Högskolan (KTH)

Microbial Cell Factories

1475-2859 (ISSN)

Vol. 14 1 12-



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