Characterization of Aspergillus niger isolated from the International Space Station

Jillian Romsdahl romsdahl@usc.edu ¹ Adriana Blachowicz ^1,2 Abby Chiang ³ Yi-Ming Chiang ¹ Jason Stajich ⁴ Markus Kalkum ³ Kasthuri Venkateswaran ² Clay Wang ^1,5

¹Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, California, USA
²Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
³Department of Molecular Immunology, Beckman Research Institute of City of Hope, Duarte, California, USA
⁴Department of Microbiology & Plant Pathology and Institute of Integrative Genome Biology, University of California-Riverside, Riverside, California, USA
⁵Department of Chemistry, University of Southern California, Los Angeles, California, USA

As strives are made toward human interplanetary exploration, a thorough understanding of how fungi respond and adapt to the various stimuli encountered during spaceflight is imperative for the health of crew. In the current study, we used a combination of genomics, proteomics, and metabolomics to characterize the molecular phenotype of a strain of Aspergillus niger isolated from the International Space Station (ISS). As a predominant ISS isolate that is frequently detected in other built environments, current and future studies of A. niger strains that have inhabited spacecraft environments will become increasingly important as the duration of manned space missions increase. The ISS isolate exhibited an increased rate of growth compared to a terrestrial strain. Whole-genome sequencing revealed increased genetic variance when compared to several other genome sequenced strains A. niger. Additionally, a distinct molecular phenotype of the ISS isolate was observed that suggests increased resistance to irradiation and oxidative stress, and an enhanced ability to acquire nutrients. Increased abundance was also observed for numerous secondary metabolites, including naphtho-gamma-pyrones, which are involved in melanin production, and pyranonigrin A, an antioxidant. These findings provide insight into the adaptive evolutionary mechanism of melanized fungal species and demonstrate the need for more studies on the biological alterations of microbes adapted to extreme spaceflight environments.