Wherever humans go, our bacterial companions will follow. It is as true in space as it is on Earth, and although we know that microbial astronauts are on the International Space Station, a group of researchers has found a new reason to worry about them.
A genomic analysis of samples taken in the toilets aboard the station, among others, revealed that some of the bacteria present on the ISS possess genes conferring resistance to antibiotics. Researchers at NASA's Jet Propulsion Laboratory pose no danger at the moment, but this is a reminder that bacteria could pose a threat in the confined environment of a space station.
In this new study, the researchers characterized the genomes of these species in detail and compared their genomes to 1,291 genomes. Enterobacter strains of the Earth. And by studying the genetic heritage of the bacteria, they have found that it would probably be resistant to antibacterial drugs.
Nitin Singh, the first author of the study, pointed out in a statement that these strains are not virulent, which means that they do not pose an active or immediate threat to astronauts. But, adds Singh, one of the strains found, Enterobacter bugandensis is an opportunistic pathogen, which means that it could potentially cause disease. A computer analysis of the species revealed that it did present a significant risk of causing harm to humans in the future.
This work was part of an effort to better understand the impact of future microbial astronauts on human life in outer space.
"Understanding how microbial life develops in a closed environment like the ISS will help us better prepare for the health problems associated with space travel," Singh said in an e-mail. "ISS provides us with a firsthand opportunity to study an often overlooked aspect of space travel: the interaction of the microbiome and the support system with the life of a spacecraft," said Singh.
The closed system aboard the space station is a unique environment for bacteria and other microbial organisms. Just as microbial species will grow, adapt and multiply here on Earth, they will do the same in space. The nooks of the equipment and storage aboard the space station are kept clean, but present microscopic organisms will find shelter and adapt to survive. As researchers have discovered, some of these adaptations could include mutations that confer resistance to antibiotics and make the bacteria extremely difficult to fight.
By better understanding the species on board the space station, researchers hope to find the best way to protect astronauts. For example, they might know when and how often to clean some equipment on board, Singh said.
Although the bacterial species present on the space station do not represent a current risk, the human immune system is compromised in space, explained Singh. Thus, during future missions in the deep space where astronauts could spend more time in space and where bacteria might have more time to adapt and multiply, the risk of 39, infection could be higher.
"Once the immune system starts to weaken, previously harmless microbes could make you sick," Singh said.
This study was published in the journal BMC Microbiology.