Cannabinoids are not the first chemical to be engineered into yeast. Others include human growth hormone, insulin, morphine, and others. To turn yeast into chemical factories, scientists had to co-opt their metabolism. Instead of turning sugar into alcohol, yeast converts sugar into other chemicals that are then changed by adding enzymes. The scientists ended up injecting more than a dozen genes into yeast, some of which were copies from the marijuana plant. After adding genes and other enzymes, the yeast produced THC and CBD.
I think this alternative method of producing THC and CBD can prove to be helpful because it eliminates excessive costs and more importantly helps the environment. In states where marijuana is legal, pesticides and use of power account for a large amount of the use of energy in the state. Using yeast would help lower the environmental and monetary cost. It will be interesting to read about in the future because the topic of THC is already rather controversial.