Graduate Student Does Groundbreaking Research

Posted on 08.23.2015

Graduate student Qusheng Jin and Professor Craig Bethke have developed an important equation to predict how fast bacteria can degrade contaminants in natural environments such as groundwater. Their work was published in the Biophysical Journal.

"If you want to predict how fast a common groundwater contaminant can be degraded, you could run an experiment in the lab. But the experiment would not necessarily indicate how fast the reaction would occur in nature. I am trying to answer the second question with my work," says Jin.

The new equation allows laboratory data to be extrapolated to explain phenomena in real-world environments by taking into account the fact that in real-world environments there is not always an abundant energy supply available for bacterial metabolism. To develop the equation, they had to take into account geochemical reaction mechanisms, chemiosmotic theory, and non-equilibrium thermodynamics. Chemiosmotic theory explains how respiration proceeds in microorganisms, and non-equilibrium thermodynamics how reaction rates are controlled by the amount of energy that is available.

"The thermodynamic part is very important because energy availability is a key difference between lab and natural environments," notes Jin.

Jin and Bethke were able to test their theory by predicting reactions that could be compared with data sets collected in nature. Since publishing the paper, Jin has received numerous telephone calls from researchers interested in applying the equation to specific environmental conditions. Jin and Bethke have several additional papers scheduled for publication in which they show how the equation can be applied.

Work on this project was a major change in research direction for Jin, who originally came to Illinois intending to work on traditional groundwater modeling. But with Bethke's encouragement, Jin took extra classes in biochemistry, civil engineering, and microbiology. These classes have allowed him to explore frontier interdisciplinary research projects. He also took advantage of the diversity of faculty on the UIUC campus and found people in several departments with whom he could discuss his research.

"I was helped by many professors on this campus," says Jin, "especially Robert Sanford in Civil Engineering and James Imlay in Microbiology. They encouraged me and spent hours talking to me. Their help was indispensable."