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Scientists use 3D printers to contain, study bacteria

Like microscopic zoos, researchers have used 3D printers to make holding cells for communities of bacteria to see how they interact to spread disease.

Researchers at The University of Texas at Austin used a digital light processing (DLP) projection system as the 3D printer to create gelatin holding cells, which are only about 30 micrometers (or microns) square or about three-quarters the diameter of a human hair.

The 3D printer was created by adapting a commercial computer projector and using the micro mirror chip inside to perform direct laser patterning of the gelatin and bacteria "ink."

UT Austin
This image shows the bacteria multiplying inside of a 3D printed gelatin cell.

"The bacteria were not made by this method; rather, they were suspended in the gelatin ink in a way somewhat similar to how fruit is sometimes suspended in JELLO," Jason Shear, a professor of chemistry and biochemistry at the University of Texas at Austin, said in an email reply to Computerworld. "The gelatin walls were then made by linking gelatin molecules together in a process controlled by laser exposure."

In a human body, bacteria commonly thrive within structured communities composed of multiple bacterial species. The University of Texas researchers said they demonstrated that a community of Staphylococcus aureus, which can cause some skin infections, became more resistant to antibiotics when they were contained within a larger community of Pseudomonas aeruginosa, a bacteria involved in various diseases, including cystic fibrosis.

The work was published this week in the Proceedings of the National Academy of Sciences.

The 3D printing enables multiple populations of bacteria to be organized within any 3D geometry, "including adjacent, nested, and free-floating colonies," the research paper explained.

Cells enclose bacteria for observation

The gelatin cells are a highly porous material that supports rapid growth of fully enclosed cellular populations and readily transmits numerous biologically active species, including polypeptides, antibiotics, and quorum-sensing signals.

"It allows us to basically define every variable," Jodi Connell, a postdoctoral researcher in the College of Natural Sciences, said in a statement. "We can define the spatial features on a size scale that's relevant to what a single bacterium feels and senses. We can also much more precisely simulate the kinds of complex bacterial ecologies that exist in actual infections, where there typically aren't just one but multiple species of bacteria interacting with each other."

Bacteria communicate through short-range physical and chemical signals that can affect communal stimulus and response, the release of spores and other adaptations.

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