AMHERST, Mass. – A team of three researchers at the University of Massachusetts Amherst recently was awarded a three-year grant from a new National Science Foundation program to pursue an unusual intersection of their disciplines, which aims to grow an entirely new field, “touch-based bacterial communication,” on their campus and beyond.
Polymer scientist Maria Santore, physicist Mark Tuominen and microbiologist Sloan Siegrist will receive $975,000 from NSF’s new “Convergence Program,” which aims to create new fields of study to address scientific issues by bringing together investigators from disciplines that are somewhat removed from each other, Santore explains.
She says, “Our program’s novelty includes a bridging of soft materials, microbiology, nano-electronics and electrical signaling to determine how bacteria respond to mechanical and electrical signals and how these signals can be exploited to manipulate bacteria. ”
In addition to the fundamental scientific research, the program will support workshops organized by the UMass Amherst team for investigators around the nation “to grow this research area into a sub-discipline in the scientific community, with our team in a leadership position, to grow additional routes of funding in the future,” Santore adds. The three call their program “Dynamic, touch-based bacteria-device two-way communication.”
Tuominen points out that at present researchers make silicon- and metal-based medical devices that interact with living tissues via signals dictated by those materials, while “living things are accustomed to chemical or biomolecular signals that travel much more slowly. Bacterial cells can respond very quickly, but the idea of interfacing with bacteria is really different. We want to identify broad models that focus on interactions at the faster time scales that bacteria offer.”
The researchers plan to build on existing experimental evidence that bacteria change their behavior based on the surface they contact, Siegrist explains. “We know they have a sense of touch, and that they respond based on that stimulus. A classic example is a biofilm, where we see a sophisticated series of steps carried out by attached cells. This is very different from how bacteria act when they are free-floating,” she says.
Santore adds that one of the new and unusual aspects of their approach recognizes that “people didn’t think bacteria could do this stuff. They are one-tenth the length, one one-hundredth the surface area and one one-thousandth the volume of mammalians cells. So the classical tools we used to use for mammalian cells just won’t work for bacteria. We need new strategies to interrogate bacterial cells.”
“Part of our project will be to build this new area,” she points out. “To do that, we must provide new methodology and instrumentation to scientists and engineers elsewhere who are working with bacterial systems. It’s a grand challenge, but being able to interface with bacteria would offer a whole new toolbox to researchers in bio-remediation, pharmaceuticals, engineering proteins or implants that probe muscle cells, and other electronic medical devices. Our program addresses the initial fundamental steps.”
Siegrist says, “We think we may be able to look at how the bacteria are feeling based on their gene expression. We hope to be able to mechanically and electronically direct cells to turn on particular genes and to have reporters to allow us to read out that gene expression in real time to control bacterial behavior. We think we can tune such variables as the stiffness or flexibility of bacterial cells, their rigidity, for example, by controlling how dense the cell wall mesh is.”
Tuominen says, “One goal of our project is to develop bacteria-integrated devices where the cells and the electronics communicate with each other. There is a lot of cool science along the way, in particular how bacterial cells interact with surfaces in their environments.” He adds that there has been “a steady evolution of tools in microbiology and nanotechnology that is pushing the frontiers of microbial electronics.”
Bacteria are so small, he points out, that it would not work for the researchers to use traditional electrodes to interact with them, but “now nanotechnology can make very small electrodes, which wasn’t so easy 20 years ago. It’s not so difficult now.”
Santore adds, “As a polymer scientist, I will be designing surfaces where the cells stick in exactly the same contact pattern at the same time so that Sloan can have as many cells as possible with exactly the same surface interaction and timing. I will engineer surfaces where bacterial cells will respond to an electrical signal. To link the mechanical and electrical response will be interesting. The first step is to observe and later to control. This has never been done in bacteria.”
Siegrist, who sees her challenge as measuring real, reliably reproducible changes in bacteria linked to stimuli, says, “They are so small there is a lot less RNA to work with, their half-life is shorter and chemical structure is different. But it’s really fun and exciting to think broadly about how to accomplish this.”
The researchers point out that the preliminary work for their NSF application was supported by the campus’s Institute for Applied Life Sciences’ Models to Medicine (M2M) Center. Peter Chien, its director, says “We are thrilled to provide support for innovative scientists to collaborate in cross-cutting new ways. Getting these types of interdisciplinary teams together with enough resources to explore bold new directions is one of the major goals of M2M and we are excited to see the outcomes of their work.”