LS9's magic bug: new genes enable one-step conversion of sugar to diesel

July 30, 2010 |

In California, LS9 announced a major scientific breakthrough that will significantly lower the cost of producing “drop‐in” hydrocarbon fuels that are low‐carbon, sustainable and compatible with the existing fuel distribution infrastructure. This breakthrough has allowed LS9 to accelerate its technology and demonstrate alkane production at pilot scale.

The discovery

In the article “Microbial Biosynthesis of Alkanes” published in Science magazine, a team of LS9 scientists announce the discovery of novel genes that, when expressed in E.coli, produce alkanes, the primary hydrocarbon components of gasoline, diesel and jet fuel. This discovery is the first description of the genes responsible for alkane biosynthesis and the first example of a single step conversion of sugar to fuel‐grade alkanes by an engineered microorganism.

The background

For over 20 years scientists have tried to identify the genes that enable particular natural organisms to directly convert biomass into alkanes. However, previous scientific research has failed to identify these genes. To solve this mystery, the LS9 team looked into the genomes of bacteria that produce alkanes in nature known as cyanobacteria. “We evaluated many cyanobacteria that made alkanes and identified one that was not capable of producing them. By comparing the genome sequences of the producing and non‐producing organisms, we were able to identify the responsible genes,” said Andreas Schirmer, Associate Director of Metabolic Engineering at LS9.

One-step vs multi-step conversion to drop-in fuels

While other biological routes to the production of renewable hydrocarbons are emerging, these other routes require costly and energy intense chemical conversion technologies such as distillation or hydrogenation. “This is a one step sugar‐ to‐diesel process that does not require elevated temperatures, high pressures, toxic inorganic catalysts, hydrogen or complex unit operations” said Steve del Cardayre, Vice President of Research and Development.

This last comment is a subtle dig  at companies like the IPO-bound Amyris Biotechnologies (or what is more politely known as a “point of differentiation”). The Amyris strategy is to commercialize farnesene on a contract manufacturing basis, then turn to farnesane, which you produce by adding hydrogen to farnesene. Farnesane is the company’s showcase diesel molecule, and forms the basis of its breakout from a speciality pharma and chemicals maker to a fuel player.

What’s farnesene again?

It’s a fragrant oil chemical. That distinctive acrid odor you detect in a Granny Smith Apple, that’s farnesene. You also find traces of it in the hops used for some very nice Czech pilasters and Irish lager beers. It’s used as a component in its own right by manufacturers around the world.

OK, back to adding hydrogen

Adding hydrogen is a popular strategy for a number of companies making renewable oils or pre-cursor fuel molecules. It’s a component part, for example, of turning renewable oils into renewable jet fuel via hydrotreating.

What’s an alkane again?

Alkanes include methane (one carbon atom), ethane (C-2), propane (C-3), butane (C-4), pentane (C-5), octane (C-8) and all the way up to an array of C-12, C-32 and even C-60 types, or isomers. Broadly they are also known as the paraffins. Butane and propane are commonly known as LPG, or liquid petroleum gas. The middle alkanes, from pentane to octane, are among the usual suspects in gasoline, while the higher alkanes, from C-9s up to C-16, are the usual suspects in diesel and aviation fuel.

So, why is that significant?

A synthetic range of C-9s to C-16s, at popular prices, is a directly converted, one-step renewable drop-in fuel.

LS9 has been working on something else, right?

Ah, Grasshopper, you remember well. A limiting factor of the LS9 and Amyris pathways has been their dependence, to date, upon C6 sugars derived from sugarcane. The major scalable sources for sugarcane feedstock are Brazil and India, which is why the Digest has been, in articles like “Bossa Nova”, noting the heavy traffic between Sao Paulo and Silicon Valley in recent years.

In February, a research team including members of the Jay Keasling lab at the DOE’s Joint BioEnergy Institute and LS9 announced a major breakthrough in their ability to make renewable diesel and other advanced biofuels directly from cellulosic biomass in a one-step process.

“We incorporated genes that enabled production of biodiesel directly,” Keasling explained in an email published by AFP. “The engineered E. coli secretes the biodiesel from the cell, which means that we don’t need to break open the cell to get the diesel out. This saves substantially on processing cost. In addition, “the biodiesel is insoluble in water, which means that it forms a separate phase when it is secreted from the engineered E. coli — it floats to the top as any oil would. This also saves on processing costs.”

LS9′s magic bug

What is it, exactly? As described above, it’s a highly engineered variant of our friend the e.coli bacteria. But don’t worry about genetically engineered e.coli rising up from the swamps and taking over cities. In LS9′s case, the magic bug is used in bioprocessing – there are no genetically engineered organisms running around in the wild, or being grown in open environments.

LS9′s other activities

In addition to alkanes and its biodiesel project, LS9 is scaling‐up its production of a portfolio of chemicals used in making industrial and consumer products – its capabilities with surfactants were the subject of Procter & Gamble’s primary interest when the two companies hooked up in a partnership last year.

Investors and partners

Investors in the company are Chevron Technology Ventures, Flagship Ventures, Khosla Ventures, and Lightspeed Venture Partners. The company also has a strategic partnership with Procter & Gamble.

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