Today, astronauts They usually quarantine before traveling to space to ensure that they do not carry with them any unwanted pathogenic microorganisms. This is for two reasons. On the one hand, it prevents them from getting sick at such a distance from a doctor who can treat them. On the other hand, we do not know how these microorganisms may behave beyond our planet, so it is better not to carry any. The problem is that, when lunar and Martian colonizations arrive, it will not be so easy to make this type of controls. Sooner or later it is likely that some pathogenic bacteria will reach there, so it is important to know what we should expect. Several studies have been done in this regard, but one of the most interesting and recent is the doctoral thesis of astrobiologist Tommaso Zaccaria, from Radboud University.
In this thesisstudies how four species of bacteria would behave on Mars. Thus, he discovers that not only could they survive. They could also become much more dangerous to humans.
Four pathogenic bacteria. The study was carried out with four species of non-extremophilic pathogenic bacteria. That is, disease-causing bacteria that are not naturally prepared to resist extreme conditions. Those chosen were Klebsiella pneumoniae, Serratia marcescens, Burkholderia cepacia and Pseudomonas aeruginosa. First, Zaccaria exposed them to a simulated Martian environment, with conditions such as very low pressure, desiccation, very high ultraviolet radiation and high concentrations of perchlorates.
There were two that held up especially well: Klebsiella pneumoniae and Serratia marcescens. For this reason, they were chosen for a second phase of the research, in which they were exposed to human immune cells. The results were quite worrying.
Martian superbacteria. When exposed to bacteria that had remained in Martian conditions, it was seen that the immune cells lost their ability to produce cytokines, proteins that are part of the defensive response. They also didn’t produce as many reactive oxygen species, which are also produced as a result of an inflammatory immune reaction. In short, it seems that Martianized bacteria become much more elusive for the human immune system.
The reasons. Zaccaria thinks that, in part, the bacteria’s resistance is due to the influence of the martian regolith. And it has nooks and crannies where water can accumulate that would help with desiccation. In addition, it protects them against ultraviolet radiation.
At the same time, they themselves develop resistance mechanisms, which help them defend themselves against Martian inclemencies, but also against the human immune system. They become superbugs.
The regolith doesn’t help at all. We have already seen that the regolith becomes a protector of bacteria. But the thing doesn’t stop there. In his study, Zaccaria exposed both live mice and human epithelial cells to simulated lunar and Martian regolith. Thus, it was seen that regolith damages the epithelial cells that normally cover the airways and, in addition, enhances inflammation and the activation of genes for mucus formation and pulmonary fibrosis.
Let us remember that one of the bacteria that survives Martian conditions is causing pneumonia. That the regolith sensitizes the lungs does not help at all. Although it should be noted that the lunar regolith turned out to be worse than the Martian one. The effects are not comparable.
‘Klebsiella pneumoniae’
Heroin yeasts. Finally, this scientist has verified how Martian conditions affect eukaryotic microorganisms. Bacteria are prokaryotes because they do not have a delimited nucleus. Yeasts, for their part, are eukaryotic microorganisms.
One of the yeasts tested in the study, Rhodotorula frigidalcoholisshowed great resistance to Martian conditions. It is capable of stopping its cell cycle and repairing DNA, so that dangerous changes do not continue to spread from one cell to another. Learning more about this mechanism could help us protect ourselves in our future as space colonizers. After all, our cells are eukaryotic.
This doesn’t end here. Zaccaria wants to study some bacterial defense mechanisms, such as the formation of biofilms or the synthesis of certain pigments. In addition, he hopes to be able to analyze how Martian conditions affect bacteria that are beneficial, such as those of the intestinal microbiota. With all this, we will be able to have a much more precise photograph to prevent the possible evils of future colonizers. When quarantines are not enough, it will be better to have a well-researched action plan.
Image | NASA | Ajay Kumar Chaurasiya
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