A promising area of biotechnology involves reenginnering bacteria into "factories" that generate beneficial pharmaceutical products. But scientists continually run into a roadblock. The natural tendency of bacteria is to produce only compounds that help it survive. When bioengineers force bacteria to produce medicines, the bacteria mutate back to their original, stable configuration because producing medicine is not a beneficial process. Therefore, the engineered bacteria never permanently and completely become pharmaceutical factories.
"The problem comes in trying to force bacteria to produce something that's not beneficial to it," explained Betsy Gammon '14. She was among six Davidson student researchers on a team charged with trying make the common E. coli bacteria produce the anti-asthma drug theophylline. They conducted their work last summer under the guidance of Davidson Professor of Biology Campbell and Professor of Mathematics Laurie Heyer, and in collaboration with other students and faculty from Missouri Western State University.
The researchers persisted through trials, tribulations, and challenges, and ultimately achieved a promising level of success. Their efforts were validated recently when they presented a poster of their project at the annual meeting of the Institute of Biological Engineering. Their effort won third place in the undergraduate poster division, as well as informal plaudits from fellow scientists. Campbell noted, "One faculty member told me we should work fast to publish our work. That usually means, ‘Because if you don't, I'm going to get to work and beat you to it!'"
Most synthetic biologists have tried to overcome the problem of bacterial evolution with an engineering-based solution. They attempt to add more DNA that will block evolution back to the original form. The Davidson team is taking a different approach. Campbell explained, "We're working to improve the ability of microbes to produce useful compounds by harnessing its natural evolution and applying natural selection to the task."
Instead of adding DNA to prevent the unwanted evolution, they harness bacteria's natural evolutionary tendencies by giving it the capacity to use a new energy source, ethanol, that "rewards" E. coli for maintaining the engineered state, and "punishes" it if it doesn't continue to produce the medicine.
Gammon explained, "We're able to manipulate genes in E. coli so that if it produces theophylline, the cell can use ethanol as an energy source. But E. coli that aren't producing theophylline aren't allowed to accept ethanol as an energy source, and they die."
There are an almost limitless number of ways to construct this "programmed evolution", so the team collaborates with mathematicians who produce mathematical models and analyze data to identify the most efficient means of building the desired microbial factory.
The research project was an original idea, not based on any published textbook or laboratory manual. To begin, all team members from both campuses met for several days on the Davidson campus to consider possible methods of turning E. coli into a pharmaceutical factory. "We started with just a vague concept, and then winnowed things down to three good ideas," said Campbell.
Small teams of students then accepted responsibility for working on different parts of the project. "It was a very steep learning curve," Gammon acknowledged. "Most of us had minimal experience with synthetic biology, and one summer is really a pretty short amount of time to complete a project like this. So it was stressful and exciting at the same time."
She continued, "But our professors created a very safe environment for learning. We had independence to try things on our own, and they were right there at the same time to help us along the way. My confidence in biology and in lab work grew a lot."
While the team didn't achieve its ultimate goal in the ten weeks allotted of producing drugs from E. coli, their mini projects were successful. Caroline Vrana got a bacterial immune system mechanism working, Becca Evans got the theophylline switch to work, Meredith Nakano and Gammon successfully used stress response to turn a gene off or on, and Ben Clarkson used pH to turn a gene off and on. Next summer's group will try to put all pieces together to complete the bacterial factory.
Student researcher Ben Clarkson said, "The big idea with the project is that is that if someone had asthma, you use E. coli to produce theophylline, rather than having to chemically synthesize the medicine."
Gammon added, "The cool thing about the project is that, theoretically, we could use E. coli to produce a wide range of products."
Campbell and Heyer have been collaborating with students in original summer research since 2001. They first steered their efforts toward synthetic biology in 2005, and for the past three summers have showcased their work at the annual meeting of the Institute for Biological Engineering.
The National Science Foundation has funded the research this coming summer, and Campbell and Heyer have recruited seven additional Davidson students to continue the research. Rather than hiring the same students for two or three summers, the Davidson professors insist on employing a completely new cadre each summer to offer a research experience to the maximum number of students.
Campbell is hopeful that this coming summer's group might achieve a commercial product. He said, "If we can make it work, it will be huge step in bioengineering microbes because we will have found a way to make E. coli maintain its own engineered state."
But in Davidson's synthetic biology lab, the journey is more important than the destination. Campbell said, "If we get a tangible product, that's great. But the number one priority is student learning. Every year we want students to come away with two results - we want them to have learned something, and had fun doing it."