Microbes used in various applications must endure extreme conditions and the manufacturing processes for long-term storage. Scientists at MIT have devised a method to enhance the resilience of microbes under such harsh environments.
Their approach involves blending bacteria with food and drug additives approved by the FDA as safe. Through their research, they have discovered formulations that can stabilize different types of microbes like yeast and bacteria, enabling them to withstand high temperatures, radiation, and industrial procedures that could harm unprotected microbes.
In a remarkable trial, some of the microbes were exposed to conditions on the International Space Station, and researchers are currently assessing how well these microbes endured those challenges.
Giovanni Traverso, an associate professor of mechanical engineering at MIT and a senior author of the study, remarked: “We aimed to stabilize organisms for extreme conditions, contemplating diverse applications such as space missions, human health, or agriculture.”
Miguel Jimenez, the lead author of the paper and an assistant professor of biomedical engineering at Boston University, noted that the study will be published in Nature Materials.
Adapting to Harsh Conditions
About six years ago, with support from NASA’s Translational Research Institute for Space Health (TRISH), Traverso’s team began developing strategies to enhance the resilience of beneficial bacteria like probiotics and therapeutic microbes. They initially analyzed 13 commercial probiotics and found that some products did not contain the expected live bacteria as stated on the label.
“Our findings indicated a noteworthy discrepancy, prompting us to explore solutions to address this issue,” explained Traverso.
For their experiments, the team targeted four different microbes: three bacteria and one yeast, including Escherichia coli Nissle 1917, Ensifer meliloti, Lactobacillus plantarum, and Saccharomyces boulardii.
When microbes are utilized for medical or agricultural purposes, they are usually converted into a powder using lyophilization. However, turning them into tablets or pills requires exposure to an organic solvent, which can be detrimental to the bacteria. The MIT researchers sought additives that could enhance the microbes’ survival during this process.
The team devised a process where microbes were combined with around 100 FDA-approved ingredients to determine which combinations improved their viability when stored at room temperature for 30 days. This investigation revealed specific ingredients, primarily sugars and peptides, that supported the survival of each microbe species.
One of the selected microbes, E. coli Nissle 1917, was further optimized. This probiotic is commonly used to treat “traveler’s diarrhea,” caused by ingesting water contaminated with harmful bacteria. The researchers discovered that by combining caffeine or yeast extract with a sugar named melibiose, they could create a highly stable formulation of E. coli Nissle 1917, known as formulation D. This mixture exhibited a survival rate over 10% after storing the microbes for six months at 37 degrees Celsius, whereas a commercial formulation of E. coli Nissle 1917 lost all viability in just 11 days under similar conditions.
