Genetically modified E coli bacteria produce ink for 3D printing programmable objects

Scientists say they have succeeded in producing programmable 3D printed objects from microbial ink produced by genetically modified E coli (Escherichia coli) bacteria.

The proof-of-concept study, led by Neel Joshi, associate professor at Northeastern University, Boston, demonstrates the technique could be used to sequester toxic chemicals from the environment or help distribute anti-cancer drugs in human bodies.

Working with Harvard University's Avinash Manjula-Basavanna and Virginia Polytechnic Institute's Anna Duraj-Thatte, Joshi demonstrated that E coli could be genetically engineered to produce nanofibers that form a kind of "microbial ink."

The resulting fibres can be concentrated and printed into 3D structures, the authors said in a paper published in Nature Communications today. These fibres can then be combined with other genetically engineered microbes (also E coli) in order to perform specific tasks via a sort of programmable functionality.

From the paper: i) single-layer grid, j) 10-layer square, k) 10-layer circle, and l) 21-layer solid cone. Insets are corresponding top views. Scale bar 1 mm

The researchers used the hydrogel to produce 3D printed objects that could secrete the anticancer drug azurin in response to a chemical stimulus. They were also able to design a material that sequestered the toxic chemical BPA when it is present in the environment.

"We demonstrate the 3D printing of functional living materials by embedding programmed E coli cells and nanofibers into microbial ink, which can sequester toxic moieties, release biologics, and regulate its own cell growth through the chemical induction of rationally designed genetic circuits. In this work, we present the advanced capabilities of nanobiotechnology and living materials technology to 3D-print functional living architectures," the study said.

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The authors also suggested the technique may one day be useful for building in space.

"The microbial ink design can be further customised for various biotechnological and biomedical applications using the ever-growing toolkit of biological parts being developed by synthetic biologists.

"Especially if combined with other materials technologies, such as those that are already incorporating living cells into structural building materials, our microbial bio-ink could also be particularly useful for structure building in space or extra-terrestrial habitats, where raw material transport is difficult, making on-demand generation of building materials from very limited resources essential," the study said.

But perhaps they will have to be careful how they — ahem — *de-bug* their programming. ®