Scientists at the University of Texas have developed a model three-dimensional (3-D) printer that can box in bacteria so that they can be studied in ways never done before.
The experiments that then can be conducted may shed some light on how bacteria interact and cause infections because they would better approximate actual conditions that the bugs encounter. The innovation could lead to better treatment for illnesses that bacteria cause in humans, according to a press release from the university. And it could be helpful for medical device or polymer-based tubing manufacturers that want their products to have features that would prevent bacteria buildup.
“It allows us to basically define every variable,” said Jodi Connell, a postdoctoral researcher in the College of Natural Sciences. “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.”
The bacterial box starts with a gelatin-based reagent in which bacteria can live and reproduce. The gelatin also contains photosensitive molecules that causes the mixture to react when struck by light. The university’s press release explains further what happens next:
The bacteria are put in the solution, and when the solution cools, the bacteria become fixed in place. Connell and her colleagues, including Jason Shear, professor of chemistry, and Marvin Whiteley, professor of molecular biosciences, identify which bacteria they want to cage and in what shape. Then they fire the laser, using a chip adapted from a digital movie projector to project a two-dimensional image into the gelatin. Wherever it focuses, a solid matrix forms.
“Then we do another layer, and another, and so on, building up,” Shear says. “It’s very simple. We’re basically making pictures and stacking them up into 3-D structures, but with incredible control. Think about the thickness of a hair on your head, and take 1 percent of that, and then take about a quarter of that. That’s about the size of our laser when it’s brought to its smallest point.”
Once the breeding box is created, the researchers can stop growth at any point to perform gene expression analysis to see which genes are turned off or on in a response to conditions in the environment. The researchers also can place different bacteria into a box to have them interact with each other, in different configuration, and different densities over different timescales and then see what happens when they are treated with antibiotics.
Think about a hospital, which we know is not a good place to be to avoid infections. There are studies that seem to indicate that infections are transmitted by very small microcolonies of bacteria, which are likely transported by equipment or staff from one part of the hospital to another. We currently know little about how this is happening. How many cells does it take? Do these microcommunities become particularly virulent or antibiotic resistant precisely because they’re small, and then in turn change the properties of bacteria on our skin or in our bodies? Now we have a means to start asking these questions much more broadly.
Source: “3-D Printed Microscopic Cages Confine Bacteria in Tiny Zoos for the Study of Infections,” University of Texas at Austin, 10/7/13
Source: “Fabricating Tiny Houses for Bacterial Microcommunities,” YouTube
Image by Connell, Ritschdorff, Whiteley, and Shear, University of Texas at Austin, used with permission.