Making Evolution Makes Microbes Make Products

Author: Cynthia Graber

Date Published: January 8, 2015

Website: Scientific American

Link: http://www.scientificamerican.com/podcast/episode/making-evolution-make-microbes-make-products/

Summary:

          Genetically engineered bacteria has proved its worth, by producing products specifically of biomedical importance, such as insulin. But the variety of products made is limited due to inefficiencies within the genetically engineered bacteria. Researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering have shed light on a new solution that could potentially broaden the variety of products made while reducing the number of environmentally harmful byproducts made using other production methods. Using a few of Darwin’s principles, researchers created a system of bacteria in which they mutated specific genes related to the production of the desired molecule. Then they altered the properties of the bacteria by making the antibiotic resistant genes “turn on” only once the bacteria had made a specific amount of the desired product. Once the system of bacteria is ready, the antibiotics are added. The bacteria that are able to produce more than the required limit survive, those who cannot manufacture the required limit are killed, reducing the number of unproductive bacteria each time. This process is repeated numerous times and is referred to by the researchers as the cycle of evolution. By putting the bacteria through the “cycle of evolution”, the researchers are able to create the desired chemicals a thousand times faster than other current production systems and are able to synthesize the desired chemical with 30 times the output of those production systems. Within time, this new method may induce genetically engineered bacteria as the main manufacturers of commercial chemicals.

Connection:

         This article connects to both of our units on Molecular genetics and our current unit on Evolution. Within our unit on Molecular Genetics we learned about the process of transformation within bacteria. In this unit we closely examined insulin, and how it was once extracted from animals and then entered into patients. Now, scientists are able to use restriction enzymes to cut a desired trait and then add it to a plasmid and then transfer the plasmid into a cell to make the desired molecule. This article explains the same process but has edited this process to make the production rates more efficient. Although the basics remain the same, scientists have applied Darwin’s theory of Natural selection to the process. Although it may appear artificial selection is going on as well, scientists say that “Because artificial selection tends to amplify unproductive cheaters, we devised a negative selection scheme to eliminate cheaters while preserving library diversity.” This being said, natural selection is present because when the bacterium is in the environment filled with antibiotics, only the highest producers survive. Here we see that the survival of the fittest is applied. Then as the survivors reproduce asexually, their offspring have an identical set of DNA and are also able to produce the desired chemicals at a high production rate. The bacterium that produce the chemicals insufficiently die out and do not reproduce therefore, only those who can produce a good quantity of the desired chemical survive on to the next cycle.The part in which the antibiotic resistant genes “turn on ” closely resembles our study of gene regulation. Similar to the lac Operon within E, coli, the microbes’ antibiotic resistant gene is turned off until the microbe has produced the required amount of the desired chemical.