Genetic and nutrient modulation of acetyl-CoA levels in Synechocystis for n-butanol production

Microbial Cell Factories

Research

Jens Nielsen¹  Danuta Kaczmarzyk²  Johan Rockberg²  Björn Renberg²  Kiyan Shabestary²  Josefine Anfelt²  Elton P. Hudson²  Mathias Uhlén³ 

[1] Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark;Department of Chemical and Biological Engineering, Chalmers Institute of Technology, Gothenburg, Sweden;School of Biotechnology, KTH, Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden;School of Biotechnology, KTH, Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden;Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark;

关键词: Cyanobacteria;    Butanol;    Biofuel;    Metabolic engineering;    Phosphoketolase;    Starvation;   

DOI  :  10.1186/s12934-015-0355-9

 received in 2015-07-17, accepted in 2015-10-07,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundThere 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.ResultsAn 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.ConclusionThese 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.

【 授权许可】

CC BY   
© Anfelt et al. 2015