Genetic engineering of cyanobacteria as biodiesel feedstock.

Abstract

Algal biofuels are a renewable energy source with the potential to replace conventional petroleum-based fuels, while simultaneously reducing greenhouse gas emissions. The economic feasibility of commercial algal fuel production, however, is limited by low productivity of the natural algal strains. The project described in this SAND report addresses this low algal productivity by genetically engineering cyanobacteria (i.e. blue-green algae) to produce free fatty acids as fuel precursors. The engineered strains were characterized using Sandia's unique imaging capabilities along with cutting-edge RNA-seq technology. These tools are applied to identify additional genetic targets for improving fuel production in cyanobacteria. This proofof-concept study demonstrates successful fuel production from engineered cyanobacteria, identifies potential limitations, and investigates several strategies to overcome these limitations. This project was funded from FY10-FY13 through the President Harry S. Truman Fellowship in National Security Science and Engineering, a program sponsored by the LDRD office at Sandia National Laboratories. 4 AcknowledgmentsThe authors of this SAND report acknowledge the support of management, particularly Anthony Martino, sponsor of Anne Ruffing's Truman Fellowship application; Eric Ackerman, Truman Fellow mentor; James Carney, Project Manager; Blake Simmons; and Ben Wu. We thank Michelle Raymer and Omar Garcia for their assistance with MCR analysis and operation of the hyperspectral confocal fluorescence microscope. We also acknowledge

Growth engineering of Synechococcus elongatus PCC 7942 for mixotrophy under natural light conditions for improved feedstock production

“…Synechococcus owing to its natural competency and high transformation efficiency has been studied as an efficient cyanobacterial host system for the production of commercially valuable hydrocarbons like ethanol, isobutyraldehyde, 2,3‐butanediol, fatty acids, fatty alcohols through genetic modifications . Despite such promises, industrial scale developments have not been reported for Synechococcus .…”

“…Currently, intensive global research has been aimed towards genetic engineering of micro‐organisms for production of hydrocarbons and value‐added compounds where photosynthetic cyanobacteria are attracting considerable interest as platform cell factories . The most explored species amongst these are Synechococcus elongatus PCC 7942 , Synechocystis sp.…”

“…Synechococcus elongatus PCC 7942 (hereafter referred as Synechococcus ) has been widely exploited as a cyanobacterial factory through genetic modification for production of fatty acids, alcohol, antioxidants, isobutyraldehyde, etc . Modifying these cells as demonstrated by McEwen et al to uptake externally supplied glucose by expressing glucose transporter protein and to perform mixotrophy is one of the promising ways to improve their biomass and so the product titers.…”