Department of Chemical and Biological Engineering

Laura Jarboe’s lab is a busy place. Although Jarboe, an assistant professor in chemical and biological engineering, just joined Iowa State’s faculty last August, she quickly became a member of the interdisciplinary research team in the newly established National Science Foundation Engineering Research Center for Biorenewable Chemicals (CBiRC).

Engineering organisms
Jarboe, who earned her PhD in chemical and biomolecular engineering at the University of California, Los Angeles, and then served as a postdoc at the University of Florida’s Center for Biorenewable Fuels and Chemicals, fits perfectly with CBiRC’s biocatalyst engineering group. The goal is to modify microorganisms, such as bacteria or yeast, to be fed into the process to produce biorenewable chemicals.

“Usually when scientists try to engineer an organism, it’s to produce a final product,” Jarboe explains. “At CBiRC, we are producing chemical precursors that will then be fed into the catalytic process to make the final product. In the traditional chemical industry these precursors come from petroleum, but by using microbial biocatalysts we can produce these chemical precursors from glucose, which basically comes from corn and is biorenewable.”

Overcoming toxic effects
For this whole process to be economically feasible, however, the biocatalyst microorganism has to produce the chemical precursors at a very high concentration. That is problematic, though, because the chemical precursors have toxic effects.

“Consequently,” Jarboe explains, “we’re going to reach the tolerance limits of our microorganism well before we get to the concentration that we need. Therefore our first focus is to try to understand why these compounds are toxic. Then we can try to engineer the organisms to become more tolerant of the chemical precursors.”

This work has implications beyond the production of biorenewable fuels, according to Jarboe. “Our approach to understanding why the precursors are toxic can be extrapolated to understanding antibiotics or any antimicrobial substance as a whole.”

Outgrowth of PhD work
In another project, Jarboe is expanding on her PhD work, where she used existing information about E. coli bacteria to study how nitric oxide, a substance produced by the body’s immune system, damages bacteria cells and also what happens when the bacteria fights off nitric oxide and is able to continue to grow. “If we can understand this cycle between the bacteria seeing the nitric oxide, but not being killed by it, that can help us identify potential drug targets,” Jarboe says.

Through statistical analysis conducted in collaboration with CBE Professor Derrick Rollins, 10 E. coli genes, whose function is unknown, were selected for further study. “My students have been cloning these genes, which means putting them into an expression vector where their expression is much higher than normal,” Jarboe explains. “If the gene is helpful in fighting off the nitric oxide, the growth lag should be decreased when nitric oxide is added. We have been working on this since September, and we have some genes that seem like they might pay off.”