What does a cell phone have in common with a single-celled bacterium?
In terms of cell-to-cell communications, the same theories and algorithms that underpin wireless networks can also describe how microbes interact.
“Bacteria communicate using chemicals,” says Bhuvana Krishnaswamy, who joined the Department of Electrical and Computer Engineering at the University of Wisconsin-Madison as an assistant professor in fall 2018. “I apply electrical engineering principles to make that information transfer more efficient.”
And by applying those principles, Krishnaswamy aims to create living sensors made from networks of bacterial cells.
“In nature, bacteria have evolved to sense their environment,” says Krishnaswamy. “We can leverage that to detect tiny amounts of potentially dangerous pathogens.”
Such living sensors might someday be able to alert doctors if an otherwise clean-looking instrument is, in fact, contaminated with nasty microbes like methicillin-resistant Staphylococcus aureus (MRSA), which can cause lethal infections.
“Most surfaces are covered with harmless bacteria, but the tiniest amount of MRSA can be fatal for a patient with a weakened immune system,” says Krishnaswamy.
And no devices capable of quickly sensing small amounts of dangerous microbes currently exist.
Electronic sensors constantly require a power source, and even the smallest batteries are orders of magnitude larger than bacteria. To create a pathogen detection system that never needs recharging, Krishnaswamy turned to living things.
Krishnaswamy plans to genetically engineer harmless bacteria so that they react to pathogens. The concept is straightforward: Sensor microbes that detect danger will send out chemical signals that induce receiver bacteria to produce an alarm. That alarm could be a burst of light, a change of color, or even something that attacks invasive microbes.
The way those chemical alerts travel between bacteria is similar to how information flows across a wireless network: Individual nodes of cells broadcast signals that are picked up by distant receivers. And those signals need to come through clearly amidst a noisy and complicated environment. By applying algorithms from communication theory, Krishnaswamy tweaks the properties of the signals as well as the characteristics of the receivers to make sure that messages transmit faithfully.
Eventually, she hopes to apply the concept directly to human health: She envisions creating a powerful and smart probiotic composed of several bacterial communities that patrol the human body, sniffing out and fighting off invading pathogens.
It’s a project that blends synthetic biology with fluid dynamics and communication theory, and that interdisciplinary spirit is part of what enticed Krishnaswamy to join the faculty at UW-Madison.
“By its nature, my research requires expertise from a variety of disciplines and willingness to work together. UW-Madison was one of the most collaborative places I visited. It was also the most receptive to improving the existing collaborative, interdisciplinary environment,” says Krishnaswamy.
Collaboration was central to Krishnaswamy’s graduate training at the Georgia Institute of Technology, where she received a master’s degree in 2013 and completed her PhD in 2018. There, she worked with mechanical engineers and biological engineers to optimize communications among bacteria growing within a microfluidic device.
She’ll build on that work here at UW-Madison, and take steps toward integrating living sensor systems with electrical outputs.
Krishnaswamy recognizes that her research is unique for the ECE department—few ECE professors work on communication networks composed of living devices—but similar questions arise for other systems where size and battery life are at a premium, such as wearable technologies.
And Krishnaswamy always keeps an open mind to exploring new avenues of research.
“I really value discussions with people from different backgrounds,” she says. “Diversity of perspectives gives me the excitement to learn something way out of my comfort zone.”
Author: Sam Million-Weaver