Kathryn Zimlich (left) and Isaac Thornton (right)
When bacteria and other microbes stick to surfaces and create slimy mats, called biofilm, they form complex communities that are often resistant to traditional disinfectants. Now, scientists in Montana State University's (MSU) Center for Biofilm Engineering are developing a tool for replicating the microbial mosaics so that innovative treatments can be studied.
“We’re excited to share the first glimpses of this technology,” said Isaak Thornton, who is earning his doctorate in mechanical engineering. Thornton, along with microbiology doctoral student Kathryn Zimlich, presented their work during the annual Montana Biofilm Meeting in Bozeman on July 12-14, which convenes researchers and industry partners for around the world to discuss the latest biofilm science.
For the past two years, Zimlich and Thornton have designed and tested a 3D printing device that can precisely lay out a grid of individual bacteria in a hydrogel, a clear, jelly like substance.
Tapping into advances in 3D printing, the researchers can map out the microbes within drops of liquid hydrogel resin and then use laser light to solidify the material, constructing a rudimentary biofilm.
“We can spatially arrange and encapsulate cells exactly where we want them,” said Thornton, who is conducting the research in the lab of Jim Wilking, associate professor in the Department of Chemical and Biological Engineering in MSU’s Norm Asbjornson College of Engineering.
So far Zimlich and Thornton have only used a single species of bacteria, but by using the 3D printer to do multiple passes, each with a different species or strain of bacteria, they could start to create the more complex and layered biofilms found in nature.
By adding fluorescent dye to the bacteria, the researchers can easily see the microbes using specialised microscopes, allowing them to study the interactions that happen among the cells.
“Even the simplest biofilm systems are complicated,” Zimlich said. “It’s like a forest where there’s lots of diversity. We’ve needed new tools to see how that diversity develops and is maintained.”
MSU Regents Professor and long-time biofilm researcher Phil Stewart has shown that a bacteria that commonly causes dangerous wound infections, will resist antibiotics because the cells in the lower level of the biofilm are cut off from oxygen and other compounds, causing them to go dormant and thereby changing their biology enough that the drug is rendered ineffective.
"One thing that’s becoming clearer is that there’s potential to treat these pathogenic bacteria by altering the interactive biofilm environment instead of trying to use harsh chemical products,” said Zimlich, whose research adviser is Matthew Fields, director of the Center for Biofilm Engineering.
Developing those treatments will require lots of testing in a controlled lab environment, which is where the new 3D printing tool comes in. “We think it’s possible to construct analogs of how these pathogenic biofilms form naturally,” said Zimlich.
That’s potentially of great interest to the attendees of the biofilm meeting. Companies like Procter and Gamble, 3M and Ecolab, as well as NASA, are eager to develop new ways of effectively controlling problem biofilms, according to Paul Sturman, who coordinates the centre's work with its roughly 30 industrial partners.
"It’s really all about helping them develop products that are useful," Sturman said. "The meeting is a great way for our members to keep apprised of the latest biofilm research. And we get to showcase the work we’re doing and are capable of doing.”
In the UK in January 2020, researchers at the University of Sheffield used biofilm research to create anti-bacterial 3D printed parts, which could potentially stop the spread of infections in hospitals and care homes.
