Fungal Biomining of Lunar Regolith simulant EAC-1A

Abstract

Space exploration roadmaps expect the development of a Lunar habitat until the end of the next decade. The success of the missions, and the sustainability of the Lunar habitat will require careful planning and use of In Situ Resource Utilization (ISRU) technologies to make the most out of the available resources. Particularly on the Moon, regolith represents a source of multiple metals. Extracting the metals through conventional methods is not ideal, due to the high energy requirements and the toxicity of the byproducts. In contrast, fungal biomining could serve as a safe and sustainable ISRU technology to obtain the same metals locally, that can be later used as construction materials, integrate energy generating systems or technologies. In this dissertation, we developed a biotechnological set-up to mobilize the metals from a Lunar Regolith Simulant (EAC-1A) to the liquid media surrounding the fungal cells. For that, we first evaluated the capacity of the fungus Penicillium simplicissimum to endure exposure to the regolith simulant, in increasing concentration from 0 to 60 % (w/v), both on Ground, and in Simulated Lunar Gravity, using a 2-D petri-dish clinostat. Media supplementation with EAC-1A did not fully impair fungal growth, showing the ability of P. simplicissimum to tolerate the regolith and possibly enable biomining processes, but altered colony morphology, and reduced the fungal colony area, biomass, and spore production during the cultures first days. After the 6th day, EAC-1A no longer included the reduction of the colony area. We developed a culture-flask bioleaching set-up that allowed the fungus to extract the metals from EAC-1A over the course of 2 weeks. Culture profiling parameters were tracked (pH, Iron, Citric Acid and Oxalic acid). Metal quantification was performed by Induced Couple Plasma Mass Spectrometry (ICP-MS). Results showed encouraging levels of metals, containing aluminium (32 mg/L), iron (68 mg/L), magnesium (159 mg/L), calcium (151 mg/L), manganese (3 mg/L) and titanium (0.02 mg/L). Chemical Precipitation allowed for a total extraction of 10 ± 3 g/L of metal Hydroxide powder. Furthermore, results show that P. simplicissimum’s colony area, biomass, and spore production are not hindered when exposed to Lunar Simulated Gravity, suggesting the possibility of carrying the biomining process both in Earth and Lunar conditions. Overall, this dissertation demonstrated a sustainable, inexpensive, and energy-efficient extraction of metals from a Lunar Regolith Simulant, preparing the foundation for further studies that implement bioleaching routines to the already established space systems.