Testing microbial biomining from asteroidal material onboard the International Space Station

Expanding human space exploration beyond Earth’s orbit necessitates efficient technologies for self-sustainable acquisition of local resources to overcome unviable resupply missions from Earth. Potential source of materials are asteroids, some of which contain valuable metals, such as platinum group elements. The BioAsteroid experiment, performed onboard the International Space Station, tested the use of microorganisms (bacteria and fungi) to carry out mining of useful elements from asteroidal material (L-chondrite) under microgravity, in support of a long-term human presence in space. The fungus Penicillium simplicissimum , enhanced the mean release of palladium, platinum and other elements from the meteorite material in microgravity, compared to non-biological leaching. However, there was large variability in the results. For many elements, non-biological leaching under microgravity was enhanced compared to terrestrial gravity, while bioleaching was unaffected. Metabolomics results revealed clear patterns that highlight the influence of space conditions on the microbial metabolism, particularly for P. simplicissimum . We identified the presence of carboxylic acids, and molecules of potential biomining and pharmaceutical interest, enhanced in microgravity. These results show a non-trivial effect of microgravity on bioleaching, highlighting the requirement of an optimal combination of microorganism(s), rock substrate, and conditions for successful biomining, both in space and Earth. ### Competing Interest Statement AM, MB and GN are employees of Kayser Italia L.t.d. All other authors declare no competing interests. * ISS : International Space Station, under microgravity condition Earth : Ground controls, under terrestrial gravity condition µg : Microgravity PGEs : Platinum group elements REEs : Rare earth elements ISRU : In situ resource utilisation BMR : BioMining Reactor EC : Experiment Container EU : Experiment Unit %NB : Element amount as percentage of sample / non-biological sample %M : Element amount as percentage of sample / total in the meteorite rock