Engineering cyanobacteria for direct biofuel production from CO2
Graphical abstract
Section snippets
Introduction: ‘light-driven conversion’
Cyanobacteria are photosynthetic prokaryotes that can use photon energy to ultimately transfer electrons from water to carbon dioxide, generating more reduced molecules in the process. The introduction of heterologous, mostly catabolic, pathways into the metabolism of cyanobacteria allows production of a wide range of fuel and commodity products from CO2, light and water [1, 2].
In the recent past this approach has matured so that by now for a large range of compounds proof of principle has been
Biofuels and other products of engineered cyanobacteria
With fuel applications in mind, there are several interesting classes of molecules available. Figure 2 gives an overview of heterologous pathways that have been introduced into cyanobacteria and the corresponding product titres that were achieved. Hydrogen, although versatile in its applications, will not be discussed in this review.
Short chain alcohols can be used as drop-in automotive fuels. The highest titres for a photosynthetically produced biofuel have been reported by Gao et al. for
General challenges for the design of production systems
A compound of interest can be produced through the introduction of a reaction that converts an endogenous metabolite. If the compound of interest is an endogenous metabolite, then its intracellular concentrations can be increased by removal of a consuming reaction. Many compounds are excreted from and/or leak out of the cytoplasm into the culture medium. For cyanobacteria, currently little is known about the underlying processes. It was shown that exporter proteins can lead to extracellular
The ideal cyanobacterial host
The ideal production host is hard to specify. Rather, different desired properties can be formulated, depending on the nature of the process.
Generally, genetic manipulation should be straightforward and engineered strains should show a high degree of stability. Growth should be fast and robust, as well as photosynthetic efficiency and carbon fixation rate could be high. To use off-gas, growth at elevated CO2 concentrations should be possible. Growth in seawater would reduce competition with the
Scientific and economic prospects
Commercial fuels usually are mixtures of compounds. Similarly, production of biofuel mixtures by photosynthetic microbes could be advantageous; even more so as many enzymes show inherent promiscuity which may lead to product diversification. Mixtures with different chain lengths were reported for alkanes [22], fatty acids [17, 18, 19, 20••, 58, 76] and fatty alcohols [23] producing strains. Furthermore, Synechococcus 7942 engineered to produce 2-methyl-1-butanol accumulated 1-propanol and
References and recommended reading
Papers of particular interest, published within the period of review, have been highlighted as:
• of special interest
•• of outstanding interest
Acknowledgements
The authors thank Filipe Branco dos Santos and Pascal van Alphen for helpful discussions and S. Andreas Angermayr for critical review of the manuscript. This review was written within the research programme of BioSolar Cells, co-financed by the Dutch Ministry of Economic Affairs.
References (76)
- et al.
Alternative routes to biofuels: light-driven biofuel formation from CO2 and water based on the “photanol” approach
J Biotechnol
(2009) - et al.
Energy biotechnology with cyanobacteria
Curr Opin Biotechnol
(2009) - et al.
Engineering a synthetic pathway in cyanobacteria for isopropanol production directly from carbon dioxide and light
Metab Eng
(2013) - et al.
Engineering a cyanobacterium as the catalyst for the photosynthetic conversion of CO2 to 1,2-propanediol
Microb Cell Factories
(2013) - et al.
ATP drives direct photosynthetic production of 1-butanol in cyanobacteria
Proc Natl Acad Sci U S A
(2012) - et al.
Physiological effects of free fatty acid production in genetically engineered Synechococcus elongatus PCC 7942
Biotechnol Bioeng
(2012) - et al.
Fatty aldehydes in cyanobacteria are a metabolically flexible precursor for a diversity of biofuel products
PLoS ONE
(2013) - et al.
Engineering of cyanobacteria for the photosynthetic production of limonene from CO2
J Biotechnol
(2014) - et al.
Engineering limonene and bisabolene production in wild type and a glycogen-deficient mutant of Synechococcus sp. PCC 7002
Front Bioeng Biotechnol
(2014) - et al.
Production of squalene in Synechocystis sp. PCC 6803
PLoS ONE
(2014)
On the use of metabolic control analysis in the optimization of cyanobacterial biosolar cell factories
J Phys Chem B
Engineering cyanobacteria for photosynthetic production of 3-hydroxybutyrate directly from CO2
Metab Eng
Engineering cyanobacteria to synthesize and export hydrophilic products
Appl Environ Microbiol
Optimization of cultural and nutritional conditions for accumulation of poly-beta-hydroxybutyrate in Synechocystis sp. PCC 6803
Bioresour Technol
Metabolic control analysis: a survey of its theoretical and experimental development
Biochem J
Direct photosynthetic recycling of carbon dioxide to isobutyraldehyde
Nat Biotechnol
Transcriptomic response to prolonged ethanol production in the cyanobacterium Synechocystis sp. PCC6803
Biotechnol Biofuels
Quantitative iTRAQ LC-MS/MS proteomics reveals metabolic responses to biofuel ethanol in cyanobacterial Synechocystis sp. PCC 6803
J Proteome Res
Wide-dynamic-range promoters engineered for cyanobacteria
J Biol Eng
A single vector-based strategy for marker-less gene replacement in Synechocystis sp. PCC 6803
Microb Cell Factories
Genome-scale modeling of Synechocystis sp. PCC 6803 and prediction of pathway insertion
J Chem Technol Biotechnol
Metabolic design for cyanobacterial chemical synthesis
Photosynth Res
Rerouting carbon flux to enhance photosynthetic productivity
Appl Environ Microbiol
Exploring metabolic engineering design principles for the photosynthetic production of lactic acid by Synechocystis sp. PCC6803
Biotechnol Biofuels
Photosynthetic production of ethanol from carbon dioxide in genetically engineered cyanobacteria
Energy Environ Sci
Cyanobacterial conversion of carbon dioxide to 2,3-butanediol
Proc Natl Acad Sci U S A
Engineering fatty acid biosynthesis in microalgae for sustainable biodiesel
Curr Opin Chem Biol
Designing and creating a modularized synthetic pathway in cyanobacterium Synechocystis enables production of acetone from carbon dioxide
Metab Eng
Oxygen-tolerant coenzyme A-acylating aldehyde dehydrogenase facilitates efficient photosynthetic n-butanol biosynthesis in cyanobacteria
Energy Environ Sci
Combinatorial optimization of cyanobacterial 2,3-butanediol production
Metab Eng
Synthesis of 2,3-butanediol by Synechocystis sp. PCC6803 via heterologous expression of a catabolic pathway from lactic acid- and enterobacteria
Metab Eng
Photosynthetic production of 2-methyl-1-butanol from CO2 in cyanobacterium Synechococcus elongatus PCC7942 and characterization of the native acetohydroxyacid synthase
Energy Environ Sci
Fatty acid production in genetically modified cyanobacteria
Proc Natl Acad Sci U S A
Improved free fatty acid production in cyanobacteria with Synechococcus sp. PCC 7002 as host
Front Bioeng Biotechnol
Microbial biosynthesis of alkanes
Science
Engineering cyanobacteria to improve photosynthetic production of alka(e)nes
Biotechnol Biofuels
Improved production of fatty alcohols in cyanobacteria by metabolic engineering
Biotechnol Biofuels
Engineering a platform for photosynthetic isoprene production in cyanobacteria, using Synechocystis as the model organism
Metab Eng
Cited by (165)
Engineering cyanobacteria for converting carbon dioxide into isomaltulose
2023, Journal of BiotechnologyDegron-mediated proteolysis of CrhR-like DEAD-box RNA helicases in cyanobacteria
2022, Journal of Biological ChemistryTransgenicism in algae: Challenges in compatibility, global scenario and future prospects for next generation biofuel production
2022, Renewable and Sustainable Energy ReviewsExploring the metabolic versatility of cyanobacteria for an emerging carbon-neutral bioeconomy
2022, Cyanobacterial Physiology: From Fundamentals to BiotechnologyApplications of cyanobacterial compounds in the energy, health, value-added product, and agricultural sectors: A perspective
2022, Cyanobacterial Physiology: From Fundamentals to Biotechnology