Fungal Germination in Space: The RayPairNyx Experiment - Investigating Radiation-Stressed Aspergillus carbonarius in Microgravity

Kurzfassung

Filamentous fungi, as Aspergillus ssp., are among the predominant microbial species found on space stations, including former Mir and the current International Space Station (ISS). Fungal contamination poses significant risks to long – term space missions, potentially leading to biodegradation of spacecraft materials and can cause health concerns in immunocompromised astronauts. The RayPairNyx experiment aims to study the germination of radiation-stressed Aspergillus carbonarius, a common crop pathogen and mycotoxin producer, in real microgravity aboard the Nyx capsule’s first flight (The Exploration Company). Here, irradiated A. carbonarius spores will be tested to examine their germination and outgrowth under the influence of radiation damage and microgravity in parallel. The scientific focus lies on testing the initial stages of spore germination of A. carbonarius spores under conditions as it has never been studied in microgravity yet. Time-resolved microscopy images will provide insights into the stages of swelling and germination of spores, enabling the determination of accumulation, swelling, germination speed, and outgrowth of hyphae. For that, spores will be dried onto polycarbonate slides before flight to ensure long-term stability, with germination induced as soon as the growth medium is added. In preparation for the RayPairNyx experiment, the eGFP-tagged strain AC49 was compared with the wildtype strain DSM 872 to determine optimal growth conditions, synthesized pigments, and survival under simulated space conditions (desiccation, microgravity, UV-C radiation, X-ray radiation). Both strains demonstrated high resistance to radiation and desiccation, and exhibited faster germination in simulated microgravity. The suitability of the transformed strain for the RayPairNyx experiment was confirmed, and potential methods for omics-based post-flight analyses were explored. This research will enhance our understanding not only of the physiology and germination itself but of the genetic and metabolic mechanisms of mold species, evaluating the threats posed by food-borne pathogens in space environments to improve safety in future space missions.