Countering Fungal Threats in Space: Advanced Surface Functionalization and Aspergillus niger Stress Responses

Kurzfassung

Microbial life has long been a persistent presence in diverse environments, prompting extensive research into the interactions between microorganisms and antimicrobial agents. In the context of human spaceflight, microorganisms such as Aspergillus niger and Penicillium spp. have been identified as predominant species in HEPA filters and dust within the International Space Station (ISS). Fungal contamination, in particular, poses significant threats to built - materials in space, potentially compromising the structural integrity of confined environments and adversely affecting human health. This highlights the critical need to understand fungal responses to stress in extraterrestrial settings to ensure the safety and longevity of future space habitats. Our study focuses on the fungal stress response to novel functionalized copper surfaces. We investigated the interactions between A. niger and innovative antimicrobial surfaces that combine actively antimicrobial copper and copper-alloys with micro-topographies created through Ultrashort Pulses Direct Laser Interference Patterning (USP-DLIP). These surfaces are engineered to exploit the antimicrobial properties of copper while enhancing its effectiveness through precisely patterned microstructures. Contact-killing assays were conducted using spores from both a wild-type and a melanindeficient mutant strain of A. niger. The results revealed an unexpected heterogeneity in spore germination responses to copper stress, indicating that A. niger exhibits a sophisticated regulation of copper homeostasis. This variability suggests that different strains of A. niger may possess distinct mechanisms for coping with copper-induced stress, which could have significant implications for the development of antifungal strategies in space. To further explore these findings, we employed various microscopy methods, including Fluorescence and Scanning Electron Microscopy (SEM). Fluorescence microscopy allowed us to observe the viability and morphological changes in A. niger spores upon contact with the coppersurfaces, while SEM provided detailed images of the spore surface structure and any physical damage incurred. These techniques helped us to correlate the physical and physiological changes in the spores with their survival rates and stress responses. In addition to microscopy, we plan to conduct detailed RNA profile analyses to uncover the molecular mechanisms underlying the observed damage. By analyzing the expression levels of genes involved in stress response, metal ion homeostasis, and spore germination, we aim to identify the specific pathways that A. niger utilizes to counteract copper-induced stress. This molecular-level understanding will provide valuable insights into the intricacies of A. niger's response to copper-induced stress and aid in the design of more effective antimicrobial surfaces. Our research addresses fungal contamination challenges in space environments and contributes to the advancement of antimicrobial materials, ensuring the safety and integrity of built - environments in space. By understanding how A. niger reacts to copper stress, we can develop robust strategies to mitigate fungal contamination on spacecraft and space habitats. Developing novel antimicrobial strategies are crucial for maintaining the health of astronauts and the structural integrity of space habitats, ultimately supporting the long-term success of future human space exploration.