The question wasn’t spurred by fanciful musing but by new techniques enabling scientists to customize an organism’s biological processes to produce novel substances. LS9’s founders saw an opportunity to leverage this emerging technology, called synthetic biology, to create “designer” microbes producing biofuels that are chemically equivalent to petroleum and diesel.
LS9 is not the only company developing renewable fuel using synthetic biology. Gevo, in Pasadena, Calif., is manipulating organisms to make butanol, Emeryville, Calif.-based Amyris Biotechnology is turning microbes into miniature factories generating diesel and jet fuel substitutes and Synthetic Genomics, in La Jolla, Calif., is developing genomes from scratch, tailored to biofuel production.
Beyond Genetic Engineering
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Synthetic biology aims to modify existing biological systems or build new systems to perform novel tasks. The technology extends well beyond genetic engineering, which typically attempts to alter a few characteristics of an organism by inserting genes from other organisms.
“Synthetic biology applies more of a systems or engineering approach,” Pal explains. Working from the bottom up, scientists define the biological processes they wish to build and identify the genes or sets of genes needed to produce the intermediate chemicals and control the biochemical reactions within an organism to execute the process. They then rewire the organism’s genetic coding, by inserting, removing and disabling genes, to meet the design specification.
New gene synthesis technology facilitates the process, allowing scientists to decipher natural DNA sequences and then replicate and modify the genes in the lab. These artificial genes are then inserted into existing organisms.
Advances in our understanding of how genes interact and simple organisms function are making the science more targeted and effective, allowing practitioners to reengineer an organism’s genetic map so that it works like a fine-tuned machine, says Kinkead Reiling, senior vice president at Amyris.
Retooling Microbes
LS9 is using synthetic biology to rewire the metabolic processes of yeast and e.coli to make its biofuels.
When microbes break down (metabolize) food into energy, excess energy produced by the process is stored. Many organisms, including humans, store excess energy by
converting fatty acids produced during metabolism into lipids (i.e. fats), what we humans know as the love handles around our abdomens.
LS9 is tapping into this storage mechanism by modifying the organism’s metabolic process to divert fatty acids into biofuel production, Pal explains.
Fatty acids are molecularly similar to hydrocarbons, which are the building blocks of gasoline, diesel and jet fuel, Pal says. By re-engineering the genetic coding of e.coli and yeast, LS9 creates a miniature assembly line (metabolic pathway) to synthesize the biofuel.
Genes missing from the microbes and required to produce intermediate substances and enzymes (which produce biochemical reactions) are inserted into the organisms. Genes producing unwanted substances or diverting energy from the biofuel production process are silenced.
To make diesel LS9’s microbes ferment (metabolize) sugars into fatty acids. But instead of converting the fatty acids into lipids, the cell’s modified metabolic process produces enzymes that combine the fatty acids with alcohol (also produced by the cell) to generate diesel, which the cell excretes.
The process consumes 65 percent less energy than ethanol production since the energy-intensive distillation process is eliminated. Unlike ethanol, diesel is not water-soluble and floats to the surface of the fermentation mixture, facilitating its removal.
LS9’s goal is to create fuel that is cost competitive with oil at $40 to $50 per barrel, Pal says. A small-scale pilot facility, planned for this year, will generate the performance and economic data to support investment in a large-scale commercial facility. Pal expects to have a product to market in three to four years.
Building Better Bugs
Modifying an organism’s genetic circuitry is only the first step in the process. The next major challenge is re-engineering the microbe to produce fuels more efficiently and in commercial quantities.
Gevo, founded in 2005, initially focused on redesigning the metabolic processes of microbes to convert waste methane gas into methanol. This work led to technology to re-engineer an organism’s metabolic pathways to increase its tolerance to toxic environments, explains Pat Gruber, company chief executive officer.
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