Yeast and the trees who love them

September 30, 2012

Super yeast turns pine trees into ethanol


1.  What first must happen to the wood chips before the yeast can be applied to them?

They must be pre-treated with heat and chemicals 

2.  What substance does the yeast consume as a process of fermentation and turn into ethanol?


3.  Why is pine such a good choice for creation of biofuels through use of the Saccharomyces cerevisiae yeast? Name two reasons.

Because of the high sugar content.  Sustainability as a source of biomass.

4.  What other crops currently use a strain of yeast to ferment the biomass to produce ethanol?

Corn and sugar cane 

5.  Why did yeast not work as a source of fermentation for softwood trees before this study?

The chemicals used to pre-treat the wood would destroy the yeast before it was able to ferment and produce ethanol.

Extension question: (or if you really want to make your students think)

Pine biomass is often referred to as slash when you see it on a logging deck.  This common waste material on a logging site is just another way a landowner can generate revenue from his timber stand.  Are there other crops that have large amounts of waste material that could be fermented for ethanol production?  Name them and describe whether they would be more difficult or easier to collect and use in a biomass fermenter.

Cotton stalks after harvest - a second tractor would have to cut and collect the hard woody stalks.  These woody stems will ferment somewhat better than true wood biomass but not as good as other crops that have thinner stalks.

Wheat straw post harvest - this is commonly baled in either rolls or square bales for use in the construction industry.  But with the downturn in the economy and the slowing of construction products the demand for straw is down.  The straw is not woody so it should be easier for the yeast to digest than woody stems.

Bean hulls? 

Pumpkin or watermelon rinds? 

Wasted vegetables from restaurants?

Hog producers are using manure to generate methane, could they also generate ethanol?