Undergraduate Engineering Team Genetically Engineers Bacteria-Based Mosquito Repellent

The Columbia iGEM team: (bottom row) Kirsten Jung, Hudson Lee, and Rachel Mintz (top row) James Gornet, Jacky Cheung, Theresa Mensah, and Kaitlin Pet.
—Photo courtesy of Rachel Mintz

A team of Columbia Engineering undergraduates recently brought home a gold medal from the International Genetically Engineered Machine (iGEM) competition for engineering a new bacteria-based, non-toxic mosquito repellent. For more than 10 years, IGEM, the top undergraduate team competition in synthetic biology, has encouraged students to work together to solve real-world challenges by building genetically engineered biological systems with standard, interchangeable parts.

The Columbia Engineering team was inspired by the lack of vaccines for many prevalent mosquito-borne illnesses, especially the Zika virus, and sought to take advantage of biosurfactant compounds known as rhamnolipids—found in the virulent bacteria Pseudomonas aeruginosa—that naturally repel mosquitos. Working closely with faculty and researchers from throughout the university, especially Professor Harris Wang of the Columbia University Medical Center, they built recombinant plasmids containing the genes that code for rhamnolipids in the pathogenic bacteria and transformed them into a different bacterial strain, Pseudomonas putida, which is harmless and can continuously produce the compounds.

“We genetically engineered the harmless bacterial strain to produce a non-trivial quantity of rhamnolipids,” said Rachel Mintz ’19, a member of the Columbia iGEM team.

Unlike traditional repellents like DEET that harm the environment, last only a short time, and tend to irritate skin, the engineered bacteria could potentially be used in new lotions that would not need to be reapplied. The team conducted human cell culture experiments and found no significant toxicity from the bacteria or rhamnolipids. They demonstrated proof of concept using actual mosquitos.

At the iGEM 2016 Jamboree in Boston in October, the team—consisting of Jacky Cheung CC ’18, James Gornet ’19, Kirsten Jung ’17, Hudson Lee CC’18, Theresa Mensah CC ’18, Mintz, and Kaitlin Pet CC ’17—competed with 5,600 participants from 42 countries. Presenting in the environmental category, they were among the 112 teams to receive a gold medal in this year’s competition.

Looking ahead, the students plan to conduct further experiments examining the impact of rhamnolipids on mice.

“Our project engaged in many exciting components of research, from human cell culture to genetic engineering to mosquito experiments,” Mintz said. “I learned so much working with the team, and we are beyond proud of what we were able to accomplish during just one summer.”

by Jesse Adams

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