Evaluation of State-of-the-Art Decontamination Techniques and Innovative Prevention Methods on the Astrobiological Model Organism Aspergillus niger

Abstract

Aspergillus niger represents one of the major fungal contaminants inside the International Space Station (ISS). It represents a hazard for human health and can compromise structural installations. It can act as an opportunistic pathogen for humans and can cause a wide variety of issues, such as skin and respiratory tract infections. It affects materials and built structures by excessive growth by releasing secondary metabolites which cause biocorrosion of materials. Fungal spores, the dispersal units and focus of this study have been observed to survive the high doses of radiation and show resistance against most of the commercial sterilization techniques. In this thesis, we tested the state-of-the-art decontamination methods: Autoclavation, UV-C irradiation, and Hydrogen peroxide (H₂​O₂​), using two strains of ​A. niger​. Corresponding results show that the wildtype strain was more capable of survival than a counterpart mutant strain with a melanin deficiency. Secondly, investigations of preventing a manifestation of fungal contamination within a closed built environment, specifically structured copper and copper-containing surfaces were tested for their effect on the viability of spores with similar results. In a nutshell, this thesis demonstrated that ​A. niger spores are capable of surviving harsh conditions, as well as the need for standardization of decontamination techniques. In conclusion, ​A. niger spores should be considered standard sterilization indicator organisms that can be used to indicate sterility in the construction of future equipment to be used in long-term space missions or any other installations that require sterile conditions.