Biomining of lunar regolith simulant EAC-1 A with the fungus Penicillium simplicissimum.

Background: On a future lunar habitat, acquiring needed resources in situ will inevitably come from the Lunar regolith. Biomining, i.e. the use of microorganisms to extract metals from the regolith, is sustainable and energy-efficient, making it highly promising for space exploration applications. Given the extensive use of filamentous fungi in industrial biotechnology, we investigated the ability of the fungus Penicillium simplicissimum to extract metals from the European Astronaut Centre lunar regolith simulant 1 (EAC-1 A), which will be used as the analogue soil at the European Lunar Exploration Laboratory (LUNA) facility at the European Space Agency (ESA) and German Aerospace Centre (DLR) site.

Results: Biocompatibility tests demonstrated P. simplicissimum tolerance to high concentrations of EAC-1 A lunar regolith simulant (up to 60%), both on Earth gravity and Lunar simulated gravity via clinorotation. We reveal that a fungal bioleaching setup using low nutrient medium (20% PDB) enables P. simplicissimum to extract metals from EAC-1 A regolith over the course of 2 weeks at room temperature. Inductively coupled plasma mass spectrometry (ICP-MS) analysis of the leachate revealed the extraction of magnesium (up to 159 mg/L), calcium (151 mg/L), iron (68 mg/L), aluminium (32 mg/L), manganese (3 mg/L) as well as traces of titanium (0.02 mg/L). The recovered metal oxide powder from the leachate, obtained via centrifugation (14,500 g, 4,000 rpm), followed by filtration (0.22 μm) and drying at 60 °C overnight, achieved a promising average of 10 ± 3 g/L. Further analysis via SEM/EDS and XRD confirmed the presence of aluminium [as boehmite (AlO(OH))], magnesium, and iron [possibly as haematite (FeO)] and magnetite [possibly as (FeO)].

Conclusion: Our study demonstrates successful fungal biomining of lunar regolith simulant EAC-1 A and emphasizes the utilization of fungal-based approaches as promising ISRU technologies in future space exploration missions.