Crop residues for the fuel tank

An especially resistant type of yeast enables ethanol to be produced from grain and corn residues

It’s a dilemma: The wheat, corn, and rapeseed that are turned into biofuels can’t serve as a source of food. In principle, using crop waste is a good alternative, because it is inedible. However, this was difficult to do until recently. Although yeast can be used to convert the sugar in the stems and leaves into ethanol, this sugar can only be dissolved by acids whose aldehydes are damaging to yeast. Now help is on the way in the form of a modified GRE20 gene. Researchers at the Massachusetts Institute of Technology have cultivated about 20,000 types of yeast, each with a differently modified GRE20 gene. After numerous tests, they found a yeast variant that is resistant to aldehyde. This yeast can turn not only corn and wheat but also straw and millet into bioethanol.