Microgravity Alters Bacterial and Phage Evolution, Offering New Avenues for Antibiotic-Resistant Treatments
A study conducted on the International Space Station (ISS) has revealed that the evolutionary interaction between bacteria and the viruses that infect them, known as phages, follows a different trajectory in microgravity compared to Earth. This research provides insights that may contribute to designing improved treatments for antibiotic-resistant bacteria and developing new phage therapies.
Research Overview
Researchers investigated the interaction between Escherichia coli bacteria and T7 bacteriophages aboard the ISS. Identical experiments were simultaneously conducted on Earth to serve as control groups. The study, which involved incubating various combinations of bacteria and phages for 25 days, was a collaboration between the University of Wisconsin-Madison and Rhodium Scientific Inc.
A research team led by biochemist Srivatsan Raman performed the Earth-based experiments. The groundbreaking findings were published in PLOS Biology.
Infection Dynamics in Microgravity
The study observed that microgravity significantly altered the speed and nature of phage infection. On Earth, phage infections typically become evident within hours, characterized by an increase in phage numbers and a decrease in bacterial counts.
In microgravity, the infection process occurred at a significantly slower rate, with effects observed after nearly a month.
This slower infection rate supports the hypothesis that reduced fluid mixing in microgravity limits encounters between bacteria and viruses. On Earth, gravity constantly stirs fluids, promoting movement and interaction. In the absence of this stirring in microgravity, encounters between the microbes become less frequent, fundamentally changing the infection dynamic.
Evolutionary Adaptations
Whole-genome sequencing of samples from the ISS revealed that both bacteria and phages developed distinct genetic mutations not observed in Earth-based samples, indicating unique selective pressures in space.
- Bacterial Adaptations: E. coli in microgravity developed mutations that provided protection against phage attacks and improved survival in the space environment. These mutations were observed in genes related to stress response, nutrient management, and changes in their surface proteins.
- Phage Adaptations: Space-based phages acquired mutations that enhanced their ability to infect bacteria and bind to bacterial receptors. They adapted to the slower pace of interaction by becoming more efficient at attaching to passing bacteria.
This coevolutionary process in microgravity resulted in different evolutionary paths compared to Earth.
Implications for Antibiotic Resistance and Phage Therapy
Further analysis revealed that the adaptations driven by the space environment might have practical applications on Earth. When tested back on Earth, specific space-adapted phages demonstrated increased activity against E. coli strains commonly responsible for urinary tract infections (UTIs). These strains are often resistant to T7 phages and current antibiotics, with over 90% of UTI-causing bacteria exhibiting antibiotic resistance. Researchers noted that this finding was unanticipated.
Experts suggest that understanding this alternative form of phage evolution could aid in developing new phage therapies. Phage therapy utilizes viruses to specifically target and eliminate harmful bacteria or increase their susceptibility to traditional antibiotics, offering a potential solution to drug-resistant pathogens.
Charlie Mo, an assistant professor at the University of Wisconsin-Madison, stated:
"The study's results indicate how space conditions can improve phage therapy activity."
Additionally, understanding these microbial dynamics is considered crucial for managing astronaut health during long-duration space missions, where spacecraft are closed ecosystems. However, the cost associated with conducting such experiments in space or simulating microgravity on Earth remains a consideration.
Broader Biological Insights
The study positions the ISS as an evolutionary laboratory, providing insights into how life adapts when fundamental forces like gravity are removed. The altered evolution of microbes in space raises questions about the origins and limits of life, including potential life forms on other planets, and enhances understanding of life's resilience across the universe.