Bioleaching of lunar regolith simulant LHS-1 using Penicillium simplicissimum for ISRU technology development

Abstract

The focus of current and future lunar missions by space agencies and industry involves not only returning people to the moon but establishing a lunar habitat to enable long-term human presence on the lunar surface. Considerations towards enabling independence from Earth resources and efficient management of resources have to be made to ensure a sustainable and cost-effective approach to space habitation. Current studies explore the concept of utilizing resources present on the lunar surface for extraction and production of materials pivotal for support of long-term human presence, further known as in-situ resource utilization (ISRU). Research includes among others the harvesting of water from ice deposits and extraction of important material from lunar regolith. This study focused on investigation of metal extraction from regolith using filamentous fungi, as biomining is more energy- and cost-efficient, as well as production of toxic byproducts is avoided, in contrast to conventional mining methods. The bioleaching capability of the filamentous fungi Penicillium simplicissimum was investigated during this study, as its bioleaching ability was demonstrated in previous research. The aim was to observe the bioleaching behaviour of the fungus in simulated lunar conditions and enhance its efficiency. It was found that it can successfully bioleach a variety of metals, including iron and aluminium, from lunar highland simulant LHS-1. Additionally, the efficiency of bioleaching seemed to increase upon sufficient nutrient supply and increasing regolith availability by exposing the fungus to a concentration of 60% (w/v) LHS-1. A positive effect of pregrowing the fungus in simulated microgravity (SMG) with subsequent utilization for biomining could not been demonstrated. Moreover, did ICP-MS analysis reveal a decrease in bioleaching efficiency observed for fungi exposed to different extends of radiation. A first design of a mathematical prediction model was created, which aids in prediction of bioleaching efficiency by P. simplicissimum for future research. The efficiency of bioleaching was demonstrated to be affected by several factors, which will have to be addressed further in future research. Especially, the interaction between the fungus and the regolith in a bioreactor has to be investigated to get a step closer to designing a novel ISRU technology enabling sustainable future lunar missions.