E. coli could convert sugar to biodiesel at 'an extraordinary rate'

When it comes to making biodiesel cheaply and efficiently enough to be commercially feasible, E. coli may prove to be "the little bacterial engine that could," say Stanford researchers.

Biodiesel can be made from plant oil or animal fat – usually the former. Used cooking oil from restaurants is common, but for biodiesel to contribute significantly to reducing fossil fuel use, there needs to be a way to mass produce it from plant-derived raw materials. The problem is that synthesizing biodiesel is complicated. That is where E. coli comes in.

The bacteria, often discussed in terms of the human digestive tract, also act as a catalyst in generating biodiesel by converting inexpensive sugars into fatty acid derivatives that are chemically similar to gasoline.

But E. coli's natural conversion capability is not up to snuff, commercially speaking, and researchers tinkering with its internal machinery have yet to boost its capability enough to cross the commercial threshold.

So Chaitan Khosla, a Stanford professor of chemistry and of chemical engineering, decided to investigate whether there might be a natural limit that holds back E. coli's conversion capabilities. In other words, does the basic catalytic engine in E. coli have enough horsepower to do the job at the needed scale?

"The good news is that the engine that makes fatty acids in E. coli is incredibly powerful," Khosla said. "It is inherently capable of converting sugar into fuel-like substances at an extraordinary rate. The bad news is this engine is subject to some very tight controls by the cell."

It turns out that like any high performance engine, the catalytic process in E. coli can only attain peak efficiency when all the controls are tuned just right. The research is described in a paper published in Proceedings of the National Academy of Sciences. Khosla is a coauthor of the paper, which is available online.

Scientists don't yet understand how all the cellular controls operate. It will require a deeper understanding of the biochemistry of E. coli than they have now to figure that out, Khosla said. But his research team is making progress homing in on the most promising part of the conversion process, thanks in part to a new approach they employed in their analysis.

The researchers managed to isolate all the enzymes and other molecular participants involved in the process that produces fatty acids in E. coli and assemble them in a test tube for study.

"We wanted to understand what limits the ability of E. coli to process sugar into oil. The question we were asking is analogous to asking what limits the speed of my Honda to 150 miles an hour and no faster?" Khosla said. "The most direct and powerful way to figure it out is to pull the biosynthetic engine out of the cell and put it through its paces in a test tube."

By doing so, the team was able to study how the enzymes involved in fatty acid biosynthesis performed when they were free from other cellular influences. That was critical to their analysis, because the products in question, fatty acids, are essentially soap, Khosla said, and too much of them would hurt the bacteria. That is why E. coli has developed some very elaborate and effective ways to contain the amount of fatty acid biosynthesis inside the cell.

The fatty acids can't be pumped directly into your gas tank – cars and trucks won't run on soap, after all – but they are an excellent precursor to biodiesel.

Biodiesel has so far lagged behind ethanol as a means of cutting fossil fuel use in vehicles because ethanol is easier and cheaper to make. But biodiesel has a higher energy density and lower water solubility than ethanol, which offer significant advantages.

"It is closer in chemical properties to a barrel of oil from Saudi Arabia than any other biologically derived fuel," Khosla said. Thus it could easily be blended into diesel and gasoline, or used alone as a bona fide transportation fuel.

If researchers can figure out how to manipulate the cellular means of production in E. coli, biodiesel could be made cheaply enough that the little engine of E. coli could end up powering a lot of larger engines at far less cost to the environment than with fossil fuels.

Xingye Yu, graduate student in chemical engineering, and Tiangang Liu, postdoctoral scholar in chemistry, contributed equally to the research and are coauthors of the paper.

Burning is better than plowing it under.

That would be true if it were only the excess that was burned. Unfortunately, we're burning the stuff we could really use. And overproduction is not just the bane of farmers -- every businessman worries about it. I think it's called risk.

We are using it after it’s ‘burned’.

One of the big, and endless, lies told about ethanol is that that’s the end of the feed stock.

It’s not, after the ethanol the improved (yes, improved) corn residue is feed to cattle, which are able to utilize it even better than ordinary corn.

The same is true, though to a less extent, for hogs, poultry and even fish.

For anyone who wants to look at some in-depth large scale studies that show the above, I can provide summaries, and links.

BTW, my tagline is there to calm down Freepers who race around shouting ‘we can’t burn our food, we can’t burn our food’.

Of course we can, we have WAY more production than we can possibly consume.

I can tell you one thing, I will NEVER put bio-diesel in either my car or truck’s tanks.

That stuff is junk ... pure and simple.

Very bad for the fuel system.

Bio-diesel, as it’s commonly made today is not suitable for modern piezoelectric injector systems. They operate at thousands of PSI and their orifices are not large enough to accommodate the thicker biodiesel.It will clog and ultimately destroy the injector systems.
Just ping FReeper Squantos, it happened to him.
Most manufacturers will void the warranty of any new vehicle that has had biodiesel damage. The manuals usually state emphatically THAT ANYTHING OTHER THAN REFINED DIESEL IS FORBIDDEN.

Older cars and trucks with MECHANICAL INJECTORS can use biodiesel just fine......

Yep...... 75 cent a gallon home brew was a $$$$ lesson in Scientific Wild Ass Guesses (SWAG) on that subject.

Buddy has a 300D mercedes, 82 I think that has two tanks. primary is refined pump diesel and aftermarket is “bio diesel and veggie oil system he bought. He runs it up for a few miles on pump fuel then switches over to his “blend” he says runs him a buck or less after all is said or done per gallon.

Then on his shutdown he switches over from his witches brew back to pump a few miles from home to purge the lines so it doesn’t crisco up on him while parked overnight or at work etc ....

As RB states........

Mechanical injectors and bio diesel ....good.

Piezo injectors and bio diesel IMO and bank account ....bad !!

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