By Dana Yamashita
E.coli is a large and diverse group of bacteria, normally associated with food poisoning. Yet most strains of E.coli are harmless, and some can actually be used to manufacture various pharmaceuticals.
Richard Bonocora, a faculty member in the Department of Biological Sciences at Rensselaer, is researching methods to grow E.coli bacteria in space, opening a new path to biomanufacturing drugs during long-term space flights. His research was recently published in Nature Microgravity.
“If we can get microorganisms to grow well in space, astronauts can use them to make pharmaceuticals on demand. This could be vital for survival on long missions where resupplying is not an option,” Bonocora said.
The team used a simulator of a space station instrument to grow E.coli, showing that it can be nurtured with methods promising to be more suitable for space travel than existing alternatives. They hope to conduct a similar experiment aboard the space station.
Bacteria like E.coli require oxygen to grow, and the method for aerating bacteria in a liquid growth medium uses an orbital shaker, a machine that horizontally shakes a platform on which the vessels containing the liquid can be stowed. The shaker relies on the force of gravity to swirl the liquid contents, which rise and fall within a flask, mixing oxygen with the liquid.
But Bonocora and his research team believe an instrument sent to the space station in July 2019 could do a better job. Inspired by the research of Rensselaer Professor Amir Hirsa, the NASA-built instrument uses shearing force, the force created at the boundary of two bodies pushing in opposite directions from one another, similar to that which occurs at the fault lines between tectonic plates. The instrument uses a syringe to dispense a drop of liquid that forms a bubble. One side of the bubble adheres to a stationary ring, while the other side adheres to a thin ring that can rotate. The rotating ring creates shear force on the surface of the bubble, swirling its contents.
On Earth, Bonocora used a knife-edge viscometer, an instrument designed by Hirsa’s group, in which the tip of a metal tube rotates — similar to the rotating ring in the space-based instrument — at the surface of liquid in a dish to simulate the shearing force. The experiment tested how well bacteria grew when aerated by the knife-edge viscometer and an orbital shaker, with both instruments used at various speeds.
At higher speeds, bacteria aerated by the knife-edge viscometer showed growth rates approaching that of the orbital shaker. Even at lower speeds, shear force produced significantly more growth than samples of bacteria that were not mechanically aerated.
“This is a viable way of growing microorganisms. We’re starting on a new path, and now we need to think about a more real-life environment, such as on the space station,” said Bonocora.
Bonocora and Hirsa were joined by Joe Adams and Shreyash Gulati in this research. “Growth of microorganisms in an interfacially-driven space bioreactor analog” was supported with funding from NASA.
