Protecting Microbes from Extreme Conditions: A Breakthrough Discovery by MIT Engineers

Imagine a world where microorganisms, essential for our health and agriculture, can withstand extreme conditions like high temperatures, radiation, and industrial processing. This is no longer a distant dream, thanks to a groundbreaking discovery by MIT engineers. They have developed a method to stabilize microbes, including yeast and bacteria, by mixing them with food and drug additives from the FDA’s “generally regarded as safe” list.

The researchers, led by Giovanni Traverso, an associate professor of mechanical engineering at MIT, began their journey six years ago with funding from NASA’s Translational Research Institute for Space Health (TRISH). Their goal was to make helpful bacteria, such as probiotics and microbial therapeutics, more resilient. They analyzed 13 commercially available probiotics and found that six of them did not contain as many live bacteria as claimed. This led them to ask: “What can we do to help the situation?”

The team chose four microbes to focus on: Escherichia coli Nissle 1917, a probiotic; Ensifer meliloti, a bacterium that fixes nitrogen in soil; Lactobacillus plantarum, a bacterium used in food fermentation; and Saccharomyces boulardii, a yeast probiotic. They set out to find additives that could improve the microbes’ ability to survive processing into tablets or pills, which requires exposure to an organic solvent that can be toxic to bacteria.

The researchers developed a workflow to mix microbes with one of about 100 different ingredients and grow them to see which survive best when stored at room temperature for 30 days. They discovered different ingredients, mostly sugars and peptides, that worked best for each species of microbe. For example, combining caffeine or yeast extract with a sugar called melibiose created a very stable formulation of E. coli Nissle 1917.

This formulation, called D, allowed survival rates greater than 10 percent after six months at 37°C, while a commercially available formulation lost all viability after 11 days. Formulation D also withstood much higher levels of ionizing radiation, up to 1,000 grays. The researchers hypothesize that the additives may help stabilize the bacterial cell membranes during rehydration.

The team then tested the microbes’ ability to survive harsh conditions and maintain their function. They found that Ensifer meliloti could still form symbiotic nodules on plant roots and convert nitrogen to ammonia after exposure to temperatures up to 50°C. Their formulation of E. coli Nissle 1917 also inhibited the growth of Shigella flexneri, a leading cause of diarrhea-associated deaths.

To further test their formulations, the researchers sent several strains of these extremophile microbes to the International Space Station, where they were exposed to extreme conditions. The samples recently returned to Earth, and the team is analyzing them to compare samples that were kept inside the ISS to those that were bolted to the outside and control samples that remained on Earth.

This breakthrough research offers a promising approach to enhance the stability of probiotics and genetically engineered microbes in extreme environments, such as in outer space. It could be used in future space missions to maintain astronaut health or promote sustainability, like promoting more robust and resilient plants for food production. The research was funded by NASA’s TRISH, Space Center Houston, MIT’s Department of Mechanical Engineering, and the Defense Advanced Research Projects Agency.

The team’s discovery has significant implications for various fields, including medicine, agriculture, and space exploration. It demonstrates the potential to create more resilient microbes that can withstand extreme conditions, making them more effective and sustainable for various applications.

Historical Context:

• The concept of using microorganisms for various applications dates back to the early 20th century, with the discovery of antibiotics and the development of vaccines.
• In the 1950s and 1960s, the use of probiotics as a treatment for various health issues gained popularity, particularly in the Soviet Union.
• In the 1980s, the development of genetically engineered microorganisms for industrial applications, such as biofuels and bioremediation, began to gain traction.
• In recent years, there has been a growing interest in using microorganisms for space exploration, with NASA’s Translational Research Institute for Space Health (TRISH) being established in 2015 to focus on the development of technologies for space health.

Summary in Bullet Points:

• MIT engineers have developed a method to stabilize microbes, including yeast and bacteria, by mixing them with food and drug additives from the FDA’s “generally regarded as safe” list.
• The researchers analyzed 13 commercially available probiotics and found that six of them did not contain as many live bacteria as claimed, leading them to develop a new method to improve the microbes’ ability to survive processing into tablets or pills.
• The team chose four microbes to focus on and developed a workflow to mix them with different ingredients and grow them to see which survive best when stored at room temperature for 30 days.
• They discovered different ingredients, mostly sugars and peptides, that worked best for each species of microbe and developed formulations that allowed survival rates greater than 10 percent after six months at 37°C.
• The formulations withstood much higher levels of ionizing radiation and were able to maintain their function even after exposure to extreme conditions.
• The research was funded by NASA’s TRISH, Space Center Houston, MIT’s Department of Mechanical Engineering, and the Defense Advanced Research Projects Agency.
• The breakthrough discovery has significant implications for various fields, including medicine, agriculture, and space exploration, and demonstrates the potential to create more resilient microbes that can withstand extreme conditions.