STTR Phase I: Carbon capture and high-value isoprene production by fast-growing cyanobacteria

The broader impact/commercial potential of this Small Business Technology Transfer (STTR) Phase I project proposes to develop cyanobacteria (blue-green microalgae) and photobioreactor (algal culture) systems that efficiently use sunlight, nutrients from wastewater, and waste carbon dioxide (CO2) to produce a sustainable, carbon-neutral source of isoprene. Isoprene is a high-value component of thousands of terpene products including synthetic rubber, pharmaceuticals, flavors, fragrances, oils, and biofuels, and has an annual market of $2 billion. Ingredients for flavors and fragrances, of which isoprenoids are a large part, are expected to reach $10 billion annually by 2017. Currently, almost all isoprene is produced from petroleum. Because of growing awareness of the dire impacts of climate change, the development of "carbon neutral" bioproducts and biofuels has become a global economic and security imperative. Renewable isoprenoids will be in demand as companies seek to mitigate their carbon footprints and improve their "green" credentials. Some bio-isoprene is being produced by microbial fermentation, but this still releases CO2, and no company currently produces isoprene photosynthetically. Thus, "photo-isoprene" produced by microalgae with energy from sunlight and carbon captured from the atmosphere or industrial flu gases will offer significant benefits for society and the environment as well as important potential for business development. This STTR Phase I project proposes to develop Synechococcus sp. PCC 7002 cyanobacteria that use CO2, sunlight, and wastewater to efficiently produce a sustainable, "green" source of isoprene (C5H8), a volatile, high-value precursor for numerous terpene products. Cyanobacteria capture rather than produce CO2. Synechococcus 7002 is among the fastest growing algae on earth, tolerates extreme light intensities that are lethal to many algae, grows in saline waters at temperatures up to 45°C, and is readily amenable to bio-engineering. These features make Synechcoccus 7002 an excellent platform for growth on wastewaters in arid regions unsuitable for crops, and cost-effective carbon capture and "photo-isoprene" production. The plan is to use a modified 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway of Synechococcus and optimized genes for isoprene synthesis to develop strains that continuously produce isoprene for weeks at rates much higher than any published for cyanobacteria. Commercialization will require further bio-engineering and photobioreactor design to maximize production and develop efficient isoprene capture. Phase I will: 1) integrate further genetic modifications to increase isoprene production 5-fold to convert 10% of captured carbon into isoprene 2) optimize photobioreactors for CO2 capture and isoprene production, and 3) develop a prototype system that captures at least 50% of the isoprene from the culture gas effluent.