You may know that a modified diesel engine can actually run on highly filtered oil left over from the deep fryer. However, that's not exactly a sustainable source of biodiesel. Many groups around the world are attempting to produce fuels and other similar compounds from highly efficient microbial organisms. Some are using fungus, bacteria, algae or like scientists from the University of Texas at Austin, yeast.
In a recent press release from Eureka Alert, they recap their work with their genetically engineered strain of yeast that converts sugars into lipids. Lipids are fat and oils that can be used as the aforementioned biodiesel, or converted into other products that are generally sourced from petroleum. This isn't ordinary baker's yeast though, but an engineered strain of a different single celled fungus called Yarrowia lipolytica.
But engineering was only the beginning. Once they had a strain that produce more lipids than its wild counterparts, they further improved things through directed evolution. This relied on effectively selecting the most efficient individuals in the population, and then allowing those to proliferate and mutate. That part was actually surprisingly simple, since the cells that produced the most lipids floated to the top of the growth medium, and the way oil floats on water.
After several cycles of this, the yeast produced 1.6 times as many lipids as the first engineered strain. Resulting in roughly 40 grams of lipids per one liter of growth medium. Since these yeast feed off of highly renewable sugar, those numbers might actually make biodiesel and other products from yeast competitive with conventional petrochemicals. Not only can this be a source for biofuel but many other lipid-based products. The scientists were able to produce various oils, polyunsaturated fats, waxes, and lubricants.
Single celled organisms are generally more efficient than multicellular organisms, so this could be a more efficient way to produce products generally sourced from plant and animal fats. In both cases this newly developed strain of yeast should help us reduce our carbon footprint, and produce many things in a more environmentally sustainable way.
