Abstract
Microorganisms are employed to mine economically important elements from rocks, including the rare earth elements (REEs), used in electronic industries and alloy production. We carried out a mining experiment on the International Space Station to test hypotheses on the bioleaching of REEs from basaltic rock in microgravity and simulated Mars and Earth gravities using three microorganisms and a purposely designed biomining reactor. Sphingomonas desiccabilis enhanced mean leached concentrations of REEs compared to non-biological controls in all gravity conditions. No significant difference in final yields was observed between gravity conditions, showing the efficacy of the process under different gravity regimens. Bacillus subtilis exhibited a reduction in bioleaching efficacy and Cupriavidus metallidurans showed no difference compared to non-biological controls, showing the microbial specificity of the process, as on Earth. These data demonstrate the potential for space biomining and the principles of a reactor to advance human industry and mining beyond Earth.
Highlights
Microorganisms are employed to mine economically important elements from rocks, including the rare earth elements (REEs), used in electronic industries and alloy production
REEs bioleached into solution were measured for all three organisms (S. desiccabilis, B. subtilis, C. metallidurans) in all three gravity conditions and for non-biological controls (Fig. 2, Supplementary Fig. 1 and Supplementary Table 2)
Statistical analysis across all three organisms and the three gravity conditions tested in space showed a significant effect of the organism (ANOVA: F(2,369) = 87.84, p = 0.001) on bioleaching
Summary
Microorganisms are employed to mine economically important elements from rocks, including the rare earth elements (REEs), used in electronic industries and alloy production. Bacillus subtilis exhibited a reduction in bioleaching efficacy and Cupriavidus metallidurans showed no difference compared to non-biological controls, showing the microbial specificity of the process, as on Earth These data demonstrate the potential for space biomining and the principles of a reactor to advance human industry and mining beyond Earth. In addition to mining beyond the Earth, advancing our understanding of microbe–mineral interactions in space could be applied to: (1) soil formation from nutrient-poor rocks[22], (2) formation of biocrusts to control dust and surface material in enclosed pressurised spaces[25], (3) use of regolith as feedstock within microbial segments of life support systems[26], (4) use of regolith and microbes in microbial fuel cells (biofuel)[22], (5) biological production of mineral construction materials[27]. There is a need to know how organisms alter ion leaching and mineral degradation in altered gravity regimens, which will occur in any extraterrestrial location
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