Team of students ventures into synthetic biology

| Staff Reporter

A team of students earned international recognition for their design of an efficient light-harvesting bacterium with the potential to improve biofuel production.

Ten students comprised Washington University’s first-ever team to enter the premier undergraduate competition in synthetic biology, the International Genetically Engineered Machine competition (iGEM). They spent the summer working together to create a photosynthetic bacterium that would vary its productivity based on the amount of light available.

For their efforts, they came home from the annual iGEM conference, held at the Massachusetts Institute of Technology at the end of October, with a gold medal.

Synthetic biology is a blossoming field that takes advantage of the wealth of genetics and molecular biology expertise that scientists have amassed in the last few decades. The goals of synthetic biologists are to manipulate existing organisms to do new tricks or work more efficiently, or even create totally novel organisms.

“What I like most about it was the applicability…I’ve done research before, but it’s all been very basic science,” senior Stephanie Chang said.

The tools and methods used in synthetic biology are run-of-the-mill, but the implications are major. Synthetic biology may be used to produce biofuels and medicines, but in theory, it could also be used to make more potent biological weapons.

Current applications range from the efficient sunlight harvester the iGEM team is creating, to entirely new organisms, such as the synthetic bacterial genome designed by J. Craig Venter in 2006.

Senior Jacob Rubens, a biology major, initiated the project while he was doing research in the laboratory of biology professor Robert Blankenship.

“I really want to study this stuff in grad school, and I didn’t really have a name for my interests…until I discovered synthetic biology, so iGEM really presented me with the opportunity to really go farther with that and try my hand at bioengineering,” Rubens said.

Other team members are biology majors and biomedical and chemical engineering students. Blankenship advised the students, along with professors Yinjie Tang and Chris Kirmaier, as well as several graduate students and postdoctoral fellows.

The team started out with the goal of doing something with bioenergy applications and a library of genetic parts at their disposal.

“We decided to work with an organism that is relatively simple, Rhodobacter sphaeroides. And that was a bit of a challenge for us because it has never been worked with before in synthetic biology or iGEM,” Rubens said.

Their project depended on the fact that many photosynthetic bacteria and algae put out light-harvesting antennae to collect sunlight more efficiently. These organisms have evolved to grow large antennae, but this is actually a problem for humans who want to use them to make biofuels: in low light, the antennae are longer than they need to be, so some cells absorb more light than they can turn into energy, resulting in lower efficiency overall.

Other researchers have tried to solve this problem by making cells with smaller antennae. But the iGEM team thought they could do better. They designed a set of genes that would allow bacteria to expand and retract their antennae according to how much light is available.

They are the first people ever to do so, according to Blankenship.

“The thing I thought was unique, and that was the brainchild of the iGEM team, was the fact that they were engineering in this dynamic response,” Blankenship said. “I don’t know of any scientists doing anything quite like that.”

To accomplish this, they relied on the Registry of Standard Biological Parts, a catalogue of gene sequences with known functions, or “biological Lego pieces,” that they could mix and match with standard techniques, Chang said. The parts they cobbled together constitute a genetic machine. Any cell expressing this DNA sequence would respond to high levels of light by building a larger light-harvesting antenna.

Their project is still underway, and they are hoping to publish a paper with their results in the future.

The bacterium they chose is not used in commercial biofuel research and development, but they took advantage of its simplicity to show that their idea works. In the future, people could adapt their genetic construct to work in other species.

Sigma Aldrich and the Office of Undergraduate Research sponsored the team.