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article imageEssential Science: Fungi become more pathogenic in space

By Tim Sandle     Nov 7, 2016 in Science
Deep space missions will carry risks to the health of astronauts and research is underway to examine risk factors like radiation, developing brittle bones and psychological effects. Also included in the mix are infections.
One area of infection of significance relates to pathogenic fungi. When astronauts embark space craft they will bring with them microorganisms. Some of these will be harmless (such as those found on human skin); others will be pathogens. While medicines will be available to treat infections, one question being asked by researchers is whether pathogens become more virulent in micro gravity conditions compared with conditions on Earth. The focus of recent research is with fungi.
Fungal diseases generally receive less attention than infections from bacteria, viruses and parasites. However, fungal diseases are ever-present and millions of people around the world are at risk from different types of fungi. However, research into fungal disease and preventative measures receives lower medical attention and lower funding, according to the Microbiology Society (as discussed in the report, titled “Human Fungal Diseases”).
In addition, earlier this year, Professor Neil Gow, who works at University of Aberdeen, told the BBC in an interview that more than one million people die from fungal infections around the world each year.
As this writer has reported previously on Digital Journal, fungal infections in humans generally relate to three types of fungi. These are: species of Aspergillus, which affects the lungs; species of Cryptococcus, which mainly attack the brain; and species of Candida, which infect mucosal membranes including in the mouth and genitals. There are, of course, other species of pathogenic fungi.
There are many perils associated with deep space missions. For instance, one concern related directly to people is the effect of prolonged time in deep space on the health of the astronauts. Here NASA has experimented on human tissue, to see how the biochemistry alters in micro gravity conditions. Other areas of research include the effects of radiation, which is an important consideration if humans ever intended to travel to Mars. In this research, a report in Wired noted that a round-trip to Mars would see astronauts subjected to radiation levels 13 times higher than the limit a person working at a nuclear power plant can receive in a year. This obviously presents a major health risk for a mission.
A further risk is with pathogenic microorganisms. In relation to this, Benjamin Knox from University of Wisconsin-Madison has been examining fungi. Knox’s research indicates that the fungus Aspergillus fumigatus (an opportunistic fungal threat to human health) grows and behaves similarly on the International Space Station compared with Earth.
The International Space Station seen from space
The International Space Station as seen from space shuttle Discovery June 11, 2008. The European Space Agency’s Jules Verne Automated Transfer Vehicle is seen at the bottom of the image
The research has been conducted at the Microbial Observatory on board the International Space Station, with a particular focus on the behavior of fungal isolates subjected to microgravity environments. The information is designed to inform how pathogenic fungi might interact with humans in closed environments.
The isolates of A. fumigatus were previously isolated from the International Space Station and these were compared with reference isolates from Earth. This fungus was selected because it is a significant and opportunistic mold pathogen of humans, especially to those who are immunocompromised.
Aspergillus fumigatus is a fungus of the genus Aspergillus  and is one of the most common Aspergillu...
Aspergillus fumigatus is a fungus of the genus Aspergillus, and is one of the most common Aspergillus species to cause disease in individuals with an immunodeficiency.
US Department of Health and Human Services
A. fumigatus is a saprotroph and one that is widespread in nature. The fungus is typically found in soil and decaying organic matter, such as compost heaps.
The analysis conducted included in vitro (performing a given procedure in a controlled environment outside of a living organism) growth and chemical stress tolerance. By comparing the Earth and space station isolates, it was concluded there were no obvious genetic differences.
However, what was of interest was that strains in space were slightly more lethal in a vertebrate model of invasive disease. However, the researchers have added a note of caution to explain that this alone does not mean there is a greater risk of infection to astronauts based on spending prolonged periods in space and that no significant changes were observed with the fungus when exposed to the environmental conditions on the space station.
In a research brief, Knox observes: “While we observed virulence differences, we speculate that it is completely within the variation that one would observe with terrestrial isolates.”
However, he also added: “There is an emerging body of literature showing a terrific phenotypic variation in A. fumigatus.” What this variation means will need to be the subject of further investigation. henotypic variation in a population of organisms can contribute to natural selection and evolution. The research forms part of a wider review of long-term consequences of microbial exposure on human health in closed human habitats.
The findings are reported to the journal mSphere and the paper is titled “Characterization of Aspergillus fumigatus Isolates from Air and Surfaces of the International Space Station.”
This article is part of Digital Journal's regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week the topic of ‘open access’ and the publishing of scientific data was discussed, with a review of how more scientific data could be made available to researchers and the general public. The previous week examined how the immune system can be developed to combat malaria.
More about Space fungi, Fungi, Space, International Space Station, Astronaut
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