Three USC professors have found a way to combat deadly bacteria through a computer-simulated study.
USC professors Priya Vashishta from the USC Viterbi School of Engineering; Rajiv Kalia from the USC Dornsife College of Letters, Arts and Sciences; and Aiichiro Nakano from Viterbi, were hired in 2002 by President C. L. Max Nikias to conduct the study.
“We were hired jointly in three separate departments,” Vashishta said. “The idea was to establish a group who would do simulations using computers. You need all three of those departments for this kind of study.”
Simulations have become an increasingly common research method. Conducting research on a computer lessens the cost of materials and shortens a lengthy, repetitive trial process, Vashishta said.
The professors, along with Aravind Krishnamoorthy, a Viterbi postdoctoral fellow, used simulations to find the optimal conditions for killing the bacteria, even with the presence of spores, which are a protective mechanism developed by bacteria to allow bacteria to withstand most harm.
“Once they go to the dormant state, nothing [can] kill them,” Nakano said. “No radiation, no chemicals — they survive. it’s extremely hard to kill in this dormant state of the spore. Basically the simulation found how much heat and how much water content is needed to make it easy to kill the bacteria.”
The study is rooted in the concept that a certain amount of water and heat cause bacteria to germinate before detecting conditions are harmful and entering spore mode, which makes bacteria impossible to kill.
“You allow it to germinate but not to go into full spore mode,” Vashista said. “So if you just barely germinate, you’ll be able to kill it. At that point of wet heat, we will kill [them], and that is the simulation.”
The computer simulation revealed that the bacteria can be killed at the optimal temperature of 90 to 95 degrees Celsius with a water concentration above 30 percent, according to Vashista.
Once the bacteria is in the right environment, they are killed with black silicon nanopillars, which Nakano described as similar to a “bed of nails.”
The research project was funded by a grant from the Defense Threat Reduction Agency, who’s looking for ways to combat bacteria as a biological weapon.
“The funding comes from the DTRA, as they are primarily interested in find out how and when these bacterial spores die,” Krishnamoorthy said. “It’s important because if you’re trying to disinfect something with the presence of this bacteria, you have to be sure that these bacterial spores die. They want to know what are the conditions in which these things die, because if you don’t kill them completely, they can come back.”
Krishnamoorthy said the study will have real-life applications. It can be used to counter biological weapons, lessen the spread of bacterial diseases and provide breakthroughs in food preservation.