In an article published today in the Proceedings of the National Academy of Sciences, researchers from the University of Texas developed a microscopic 3D printing strategy to study communication between different species of bacteria.

It has long been known that bacteria communicate with each other by releasing and absorbing chemicals in their surroundings - but these chemical signals travel only very small distances, which has made studying them on traditional 2D plates challenging.

The researchers used a laser-based technique to build containers in gelatin for bacteria in almost any 3D shape.

Gelatin, a very porous material, allows chemicals to pass freely between the containers.

“We believe this development will become a valuable tool in understanding behavioural complexity in polymicrobial infections, such as those that can take root in chronic wounds,” the paper’s lead author and professor of chemistry Jason Shear said.

“How arrangement may influence the virulence of populations within such communities is of fundamental scientific interest, and insights that may derive from systematic studies has the potential to inform therapeutic strategies.”

Mark Blaskovich, a senior research officer at the Institute for Molecular Bioscience at the University of Queensland (who was not involved with the study), also noted the method provides a very good way of studying how bacteria interact chemically.

“In the real world, bacteria grow under a wide range of conditions,” he said.

“They are often found in small spaces surrounded by tissue and cells, and in the presence of other bacteria. Simulating this in the laboratory is very difficult, which is why our understanding of how bacteria communicate with each other or behave in different environments is very limited.”

Jodi Connell

Dr Blaskovich was concerned that the new technique will not be widely available for research. He notes that it requires highly specialised equipment, too expensive for most labs.

An important use of the 3D printing method will be in the battle against antibiotic resistant bacteria, the so-called “superbugs”.

“The authors of the publication have already shown that small populations of one type of drug-resistant bacteria can directly influence a non-resistant strain - not by passing on genes for antibiotic resistance, but by chewing up the antibiotic before it reaches the other bug,” Dr Blaskovich said.

Communication between bacteria also controls how virulent an infection turns out to be. Understanding how bacteria talk to each other will help patients with many diseases, like cystic fibrosis.

Andrea O'Connor, associate professor of chemical and biomolecular engineering at the University of Melbourne and also not involved with the study, said a wide range of 3D printing techniques are currently being investigated, enabling the printing of biomaterials including polymers, hydrogels, ceramics and metals.

“3D printing technologies have many potential applications in biomedical research and in development of medical devices, biosensors, drug delivery systems and even in repair and regeneration of tissues and organs,” she said.

“Recently researchers have also developed methods to print biological cells and cell aggregates in 3D arrangements like sheets and hollow tubes. The work reported in this paper takes an alternative approach - instead of printing the cells themselves, the authors suspended the cells in a gel and then used a laser beam to crosslink or set regions of the gel surrounding selected bacterial cells.”