Engingeering Brewer's Yeast to Produce Diesel

Beer? Not quite. Try fermented sugar water that produced diesel instead of alcohol

A recent hour long BBC documentary called Playing God showcases cutting edge science concerning the production of synthetic organisms that can help produce things in ways that nature cannot. The first example are the 'spider goats' which are normal goats but they were created to be able to produce one extra little protein in their milk, the same protein that is spider silk, that when extracted, can be turned into this spider silk, a thread that is stronger than anything we can produce.

I was surprised when they mentioned the manipulation of Brewer's Yeast. The way the yeast basically works is that you feed yeast a sugary water and it produces CO2 and alcohol. In beer we allow the CO2 to pass through an airlock, and the liquid becomes alcoholic, and we drink the alcoholic beverage in a pint glass.

Under the microscope: Diesel rising to the top of the fermenting sugar water

The documentary takes us to a synthetic biology lab where scientists have engineered brewer's yeast to produce diesel instead of
alcohol. They are "reprogramming [the] yeast to make and meet the petroleum needs of the world." We get to see the lab, the pilot system, and within about a days timing the yeast has fermented the sugar water and instead of an alcoholic drink, we've got diesel. The diesel rises to the top of the liquid because it's lighter than the water, and then they separate it. Pretty extraordinary technology. An article in The Guardian that "diesel seeps out of every cell. This synthetic biodiesel is already used to power trucks in Brazil. Amyris's ambition is to scale up from pilot plants to industrial-scale production."

The extraction of diesel on the left, and collection of yeast on the right.

The documentary does brings up a number of concerns, including the large amounts of land it could take to grow sugar to feed the yeast (and many other synthetic organisms). The whole time I was thinking about Brettanomyces, Lacto, and Pedio which have been known to get into beer where it's unwanted, thus making the beer "infected." This Diesel-Brewer's-Yeast would certainly be an unwanted infection if it were to escape the lab and end up in a brewery!

Images are still-shots taken from the BBC Documentary.
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