Microbes are ubiquitous here on Earth and can survive a range of environmental conditions encompassing broad ranges of temperature, pH, salinity, energy, and nutrient levels. Not only do these microbes flourish in such a wide range of circumstances on Earth, but they are also able to withstand the harsh environment of space, which includes intense radiation, vacuum pressure, temperature fluctuations, and microgravity.
The International Space Station (ISS) is home to millions of bacteria and other microbes. Most likely, these microorganisms have been introduced to the ISS from Earth – transferred with the arrival of new crew or cargo. Understanding the types of bacteria that may survive and even thrive in this harsh environment is crucial to ensure that the health of the astronauts working on the ISS is not threatened. Moreover, this research offers a deeper understanding of microbial dynamics in controlled terrestrial environments too, such as in hospital ICU’s and surgical theatres.
Genetically and functionally distinct
Recent research by Dr. Venkateswaran of NASA’s Jet Propulsion Laboratory describes thirteen new strains of bacteria isolated from the unique environment of the ISS. The bacteria known as E. bugandensis, is a species of Enterobacter. The researchers carried out a comprehensive study to understand the genomic intricacies of ISS-derived E. bugandensis in comparison to terrestrial strains.
The results showed that the ISS-isolated strains had been significantly altered in the conditions of space, and no longer resembled their Earth counterparts.
They found that the genomes of the space bacteria contained thousands of single nucleotide polymorphisms (SNPs), several insertions and deletions, and hundreds of complex mutations, rarely detected in Earth genomes.
These genetic alterations relate to changes in for example amino acid transport and metabolism, cell biogenesis, mobilome elements (which includes prophages and transposons), and transcription factors. Such variations may translate to functional differences allowing these strains to survive and thrive in the extreme conditions of space.
Accelerated microbial resistance
Importantly, Dr. Venkateswaran and colleagues discovered that the ISS-derived E. bugandensis had developed formidable resistance to antimicrobial treatments. In the E. bugandensis genomes collected from the ISS, the researchers looked for antibiotic resistance genes, and found that
“…these genomes harbour resistance to 23 different multidrug classes, including cephalosporin, cephamycin, fluoroquinolone, and nitroimidazole antibiotics.”
Further studies were conducted which identified four distinct mechanisms of antibiotic resistance including antibiotic target alteration, antibiotic efflux, reduced permeability to antibiotics, and antibiotic inactivation. Moreover, certain organisms utilised combinations of these mechanisms to gain resistance against the antibiotics.
Interestingly, it appears that the unique stresses of the space environment, distinct from any on Earth, could be accelerating these genomic adaptations, and bolstering the pathogen’s resistance to antimicrobial treatments.
The findings highlight the necessity for robust preventive measures to mitigate risk associated with potential pathogenic threats. Furthermore, understanding the survival mechanism of these organisms holds promise both for safeguarding astronaut well-being as well as managing the rise in hospital infections.
Antimicrobial resistance poses a significant challenge for health systems worldwide, and innovative strategies for incentivising antibiotic development are much in demand. Several options have been proposed including subscription models, annual revenue guarantees, market entry rewards, milestone payments, and transferable exclusivity extensions. The European Union (EU) has several initiatives to address antimicrobial resistance in 2025 and beyond, including the One Health Antimicrobial Resistance (OHAMR) partnership and the revision of EU pharmaceutical legislation. It will be an interesting year to see which proposals for tackling antimicrobial resistance are adopted, including whether we will see and changes to IP or exclusivity provisions.
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