Powering a large bioreactor in a remote country, the middle of a battlefield or on a spacecraft is about as hard as it sounds. Right now, many medicines and chemicals require this traditional fermentation technology. However, a team of chemical engineers is working on a hydrogel-based alternative.
“Our technology addresses a strong limitation in the fields of synthetic biology and bioprocessing, namely the ability to provide a means for both on-demand and repeated-use production of chemicals and antibiotics from both mono- and co-cultures,” said Hal Alper, professor at the University of Texas who collaborated with the University of Washington’s Alshakim Nelson on the research and paper.
A hydrogel scaffold that can flow like a liquid but harden upon exposure to UV light is at the heart of Alper and Nelson’s new system. Microbial biofactories can be embedded into the solid scaffold of the hydrogel once ready. As a crosslinked polymer, the hydrogel can either be 3-D printed or manually extruded. The resulting polymer network is large enough for molecules and proteins to move through it, but the space is too small for cells to leak out.
Even so, many medicines, including antibiotics, have a fixed shelf like and require very specific storage conditions. The researchers overcame this limitation by freeze-drying the entire hydrogel system. The sudden blast of low temperature and pressure preserves the fermentation capability of the biofactories until needed. To revive the hydrogel and start cell production again, users simply need to add water, sugar and other basic nutrients.
“The portability of a biofactory that can synthesize these molecules makes the hydrogel system especially useful in remote places that don’t have access to refrigeration to store medications. It would also be a small and compact way to maintain access to several medications and other essential chemicals when there is no access to a pharmacy or a store,” the researchers said.
A unique attribute that further sets the hydrogel-based system apart from bench-based bioreactors is its ability to combine multiple different types of organisms while keeping them separated to prevent one organism from taking over or killing the others.
During tests, the research team showed they could control the dynamics of the system, keeping the growth of multiple cell types balanced. Importantly, they also verified continuous, repeated use of the system—with yeast cells—over the course of an entire year without a decrease in yields, indicating the sustainability of the process over time.
The system’s ability to synthesize molecules and other chemical compounds goes beyond the reaches of medicine, impacting the production of vitamins, perfumes, fuels and more.
“This technology can be applied to a wide range of products and cell types. We see engineers and scientists being able to plug and play with different consortia of cells to produce diverse products that are needed for a specific scenario,” said Alper. “That’s part of what makes this technology so exciting.”
Photo: 3-D-printed hydrogel lattice. Credit: University of Texas