Is E.Coli the answer to better biofuel?

It’s rare that we think of anything positive when we hear about the bacteria E. coli.

Sometimes researchers will use a laboratory-adapted version of E. coli that lacks the features that cause humans to get sick, but grow just as fast. As it turns out, that quality is what also allows it to transform into the tiniest of factories — when its chemical production properties are harnessed, E. coli has the potential to produce biofuels, pharmaceuticals and other useful products.

A team from the School of Engineering & Applied Science at Washington University in St. Louis has now figured out a way to make the production of certain biofuels in E. coli much more efficient. The new method, developed by Fuzhong Zhang, assistant professor in the Department of Energy, Environmental & Chemical Engineering, and his team, cuts out a major stumbling block to production process.

“It’s a critical step that we’ve figured out how to solve this problem,” Zhang said.

Branched-chain fatty acids (BCFA) are important precursors to the production of freeze-resistant or improved cold-flow biofuels. However, making it in bacterial hosts is difficult. It’s co-produced with different compounds called straight-chain fatty acids (SCFA), which have inferior fuel properties. Past attempts to engineer E. coli that churned out BCFA also made a large amount of SCFA, and made it difficult to isolate the BCFA for future use.

“From the process aspect, common bacteria produce mostly SCFA,” said Zhang. “That is really not the best fuel to use. Previously, the best you could do was a 20% BCFA concentration. Then you needed to use some additional chemical processes to separate the BCFA from the SCFA and enrich it. It consumes so much energy that it’s not cost-effective.”

Instead, the team created a new organism that could produce close to 100% BCFA.

Zhang’s lab has previously researched methods to reduce SCFA concentrations in E. coli, but their current work build on it further by developing two different protein pathways that chemically affect the bacteria. This is what let the team fix what it called a bottleneck in the BCFA production line. The protein pathways enabled the E. coli to boost its BCFA manufacture to 80% of all fuel products.

“It’s a higher quality,” said Gayle Bentley, a doctoral student in Zhang’s lab, and the paper’s lead author. “A lot of people have been making these SCFA fuels, and while that’s important work, they don’t have the improved qualities like we’re generating. The difference is quite significant.”

The applications for this breakthrough have potential to expand to other products derived from fatty acid compounds.

“The compounds we’ve made as fatty-acid forms are beneficial as a nutraceutical, effective as an anti-tumor compound,” said Bentley. “It’s also been shown to be effective to prevent and treat neonatal necrotizing enterocolitis. These compounds are really expensive to derive from their original source but using this platform may actually make it more economically feasible.”