Metabolic engineering of cyanobacteria for ethanol production

Abstract

Development of renewable energy is rapidly being embraced by our society and industry to achieve the nation's economic growth goals and to help address the world's energy and global warming crises. Currently most of the bioethanol production is from the fermentation of agricultural crops and residues. There is much debate concerning the cost effectiveness and energy efficiency of such biomass based ethanol production processes. Here, we report the creation of a Synechocystis sp. PCC 6803 strain that can photoautotrophically convert CO 2 to bioethanol. Transformation was performed using a double homologous recombination system to integrate the pyruvate decarboxylase (pdc) and alcohol dehydrogenase II (adh) genes from obligately ethanol producing Zymomonas mobilis into the Synechocystis PCC 6803 chromosome under the control of the strong, light driven psbAII promoter. PCR based assay and ethanol production assay were used to screen for stable transformants. A computerized photobioreactor system was established for the experimental design and data acquisition for the analysis of the cyanobacterial cell cultures and ethanol production. The system described here shows an average yield of 5.2 mmol OD 730 unit À1 litre À1 day À1 with no required antibiotic/selective agent.

A Novel Mechanism, Linked to Cell Density, Largely Controls Cell Division in Synechocystis

“…nutrients and light; Kim et al, 2011;Lea-Smith et al, 2014;Burnap, 2015;Touloupakis et al, 2015;van Alphen and Hellingwerf, 2015). Understanding of the factors controlling the limitation of Synechocystis growth would facilitate the use of this strain as a cell factory (Yu et al, 2013) for the production of biomass (Joseph et al, 2014), pigments (Sekar and Chandramohan, 2008), secondary metabolite natural products (Frommeyer et al, 2016), biofuel (Dexter and Fu, 2009;Baebprasert et al, 2011;Liu et al, 2011), and other high-value compounds.…”

Design, Engineering, and Construction of Photosynthetic Microbial Cell Factories for Renewable Solar Fuel Production

“…Cyanobacteria have been genetically engineered and demonstrated to produce H 2 (Tamagnini et al 2007;Baebprasert et al 2011;Ducat et al 2011a), ethanol (Deng and Coleman 1999;Dexter and Fu 2009), 1-butanol (Lan and Liao 2011), isobutyraldehyde and isobutanol (Atsumi et al 2009), isoprene (Lindberg et al 2010), ethylene (Takahama et al 2003), sugars, and lactic acid (Niederholtmeyer et al 2010)-for recent reviews, see Angermayr et al (2009) and Ducat et al (2011b).…”

125th Anniversary Review: Fuel Alcohol: Current Production and Future Challenges

“…These do not involve genetic manipulation strategies and include: sterol pre-enrichment (preoxygenation, mild aeration); mineral preconditioning of yeast (Mg, Zn enrichment); ethanol adaptation (in chemostats); pre heat-shocks to confer thermotolerance; and salt preconditioning to confer osmotolerance 63 . Some naturally robust indigenous yeast (e.g., distillery resident) can Certain species of blue-green algae (cyanobacteria) can be metabolically engineered to produce ethanol, potentially from CO 2 , sunlight and seawater 24,31 . Table XIII.…”