Exposure to elevated relative humidity in laboratory chambers alters fungal gene expression in dust from the International Space Station (ISS)
Abstract Microorganisms are present in all occupied indoor environments, including homes on Earth and within specialized systems like the International Space Station (ISS). Microbes when exposed to excess moisture, such as from an unexpected ventilation system failure, can undergo growth that is ass...
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Nature Portfolio
2025-08-01
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| Online Access: | https://doi.org/10.1038/s41598-025-09534-6 |
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| author | Neeraja Balasubrahmaniam Nicholas Nastasi Bridget Hegarty John M. Horack Marit E. Meyer Sarah R. Haines Karen C. Dannemiller |
| author_facet | Neeraja Balasubrahmaniam Nicholas Nastasi Bridget Hegarty John M. Horack Marit E. Meyer Sarah R. Haines Karen C. Dannemiller |
| author_sort | Neeraja Balasubrahmaniam |
| collection | DOAJ |
| description | Abstract Microorganisms are present in all occupied indoor environments, including homes on Earth and within specialized systems like the International Space Station (ISS). Microbes when exposed to excess moisture, such as from an unexpected ventilation system failure, can undergo growth that is associated with material degradation and negative health effects. However, we do not yet understand how exposure of these microbes to excess moisture alters their function. A de novo metatranscriptomic study was performed using dust collected from the US air filtration system of the ISS and incubated in laboratory chambers on Earth at different equilibrium relative humidity (ERH) levels. Changes in fungal function (gene expression) were significantly associated with moisture (adonis2 p = 0.0001). Secondary metabolism and fungal growth genes were upregulated (FDR-adjusted p ≤ 0.001, log2FC ≥ 2) at elevated ERH compared to 50% ERH. Elevated moisture conditions showed upregulation of aflatoxin and fungal allergen genes such as Asp f 4 (log2FC = 26.4, upregulated at 85% ERH compared to 50%) and Alt a 7 (log2FC = 2.98, upregulated at 100% ERH compared to 50%). Our results demonstrate that understanding microbial functional changes in response to elevated moisture will help develop more robust microbial monitoring standards for spacecraft environments to protect astronaut health and spacecraft integrity in low-Earth orbit and beyond. |
| format | Article |
| id | doaj-art-fca3264fee9f4989b088be3fc6e583fa |
| institution | Kabale University |
| issn | 2045-2322 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Nature Portfolio |
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| spelling | doaj-art-fca3264fee9f4989b088be3fc6e583fa2025-08-20T04:03:02ZengNature PortfolioScientific Reports2045-23222025-08-0115111210.1038/s41598-025-09534-6Exposure to elevated relative humidity in laboratory chambers alters fungal gene expression in dust from the International Space Station (ISS)Neeraja Balasubrahmaniam0Nicholas Nastasi1Bridget Hegarty2John M. Horack3Marit E. Meyer4Sarah R. Haines5Karen C. Dannemiller6Environmental Sciences Graduate Program, The Ohio State UniversityEnvironmental Sciences Graduate Program, The Ohio State UniversityDepartment of Civil and Environmental Engineering, College of Engineering, Case Western Reserve UniversityDepartment of Mechanical and Aerospace Engineering, College of Engineering and John Glenn College of Public Affairs, The Ohio State UniversityNASA Glenn Research CenterDepartment of Civil and Mineral Engineering, University of TorontoDepartment of Civil, Environmental and Geodetic Engineering, College of Engineering, The Ohio State UniversityAbstract Microorganisms are present in all occupied indoor environments, including homes on Earth and within specialized systems like the International Space Station (ISS). Microbes when exposed to excess moisture, such as from an unexpected ventilation system failure, can undergo growth that is associated with material degradation and negative health effects. However, we do not yet understand how exposure of these microbes to excess moisture alters their function. A de novo metatranscriptomic study was performed using dust collected from the US air filtration system of the ISS and incubated in laboratory chambers on Earth at different equilibrium relative humidity (ERH) levels. Changes in fungal function (gene expression) were significantly associated with moisture (adonis2 p = 0.0001). Secondary metabolism and fungal growth genes were upregulated (FDR-adjusted p ≤ 0.001, log2FC ≥ 2) at elevated ERH compared to 50% ERH. Elevated moisture conditions showed upregulation of aflatoxin and fungal allergen genes such as Asp f 4 (log2FC = 26.4, upregulated at 85% ERH compared to 50%) and Alt a 7 (log2FC = 2.98, upregulated at 100% ERH compared to 50%). Our results demonstrate that understanding microbial functional changes in response to elevated moisture will help develop more robust microbial monitoring standards for spacecraft environments to protect astronaut health and spacecraft integrity in low-Earth orbit and beyond.https://doi.org/10.1038/s41598-025-09534-6FungiMicrobial functionMicrobiomeMoistureMoldSpacecraft |
| spellingShingle | Neeraja Balasubrahmaniam Nicholas Nastasi Bridget Hegarty John M. Horack Marit E. Meyer Sarah R. Haines Karen C. Dannemiller Exposure to elevated relative humidity in laboratory chambers alters fungal gene expression in dust from the International Space Station (ISS) Scientific Reports Fungi Microbial function Microbiome Moisture Mold Spacecraft |
| title | Exposure to elevated relative humidity in laboratory chambers alters fungal gene expression in dust from the International Space Station (ISS) |
| title_full | Exposure to elevated relative humidity in laboratory chambers alters fungal gene expression in dust from the International Space Station (ISS) |
| title_fullStr | Exposure to elevated relative humidity in laboratory chambers alters fungal gene expression in dust from the International Space Station (ISS) |
| title_full_unstemmed | Exposure to elevated relative humidity in laboratory chambers alters fungal gene expression in dust from the International Space Station (ISS) |
| title_short | Exposure to elevated relative humidity in laboratory chambers alters fungal gene expression in dust from the International Space Station (ISS) |
| title_sort | exposure to elevated relative humidity in laboratory chambers alters fungal gene expression in dust from the international space station iss |
| topic | Fungi Microbial function Microbiome Moisture Mold Spacecraft |
| url | https://doi.org/10.1038/s41598-025-09534-6 |
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