Light Helps Yeast Produce Fuel


By Eleanor Jennings

Science-based learning has been fundamental to major breakthroughs and discoveries. Using light to control cells is yet another example. Through genetic engineering, neuroscientists have learned how to use light to control neurons, leading to huge opportunities for better understanding the human brain and its function. Now scientists are applying similar methods and using the theories of optogenetics, or the study of light to control genes, to modify the metabolism of yeast so it produces chemicals that could one day be used commercially.

Not Just for Bread and Wine

Yeast are simple, single-celled microorganisms instrumental in the creation of everyday foods and beverages. Through fermentation, normal yeast cells transform sugar into carbon dioxide. It’s what makes bread rise. Yeast cells can also transform sugar into ethanol, which is what produces the alcohol in wine and beer. Simultaneously, they produce miniscule amounts of isobutanol, a chemical that can be used to fuel vehicles.

Optogeneticist Jose Avalos and fellow team members at Princeton University have figured out that it is possible to genetically engineer yeast cells to produce large quantities of valuable isobutanol, without drowning them in it. As every good detective knows, the solution to an investigation is often the simplest one. In their case study, the team of researchers demonstrated the use of light as an on-off switch to control the type of alcohol produced by yeast. By alternating exposure of the yeast between blue light and darkness, they determined the right balance to keep the yeast alive while also producing more isobutanol than normal.

This is a brand new approach that avoids chemicals and further reliance on genetic engineering. Once a light-responsive bacterium gene is inserted into yeast DNA, turning on the light encourages ethanol production in cells while darkness stimulates the creation of isobutanol.

This may become a targeted, efficient, and inexpensive way to create valuable chemicals for use in fuel without a huge amount of effort. It needs more study, but it’s an interesting twist in the use of a simple light switch to solve a complex problem.

Discussion Questions

  • How is isobutanol used in fuel? What are other sources of isobutanol?
  • How does a scientist insert a gene into DNA?
  • Discuss other forms of genetic engineering that you’ve heard of lately.
  • Can you think of any future benefits or problems that may be a result of genetic engineering?


  • Miniscule
  • Neuron
  • Metabolism
  • Fermentation