Space station biomining experiment demonstrates rare earth element extraction in microgravity and Mars gravity

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.

Microbially-Enhanced Vanadium Mining and Bioremediation Under Micro- and Mars Gravity on the International Space Station

“…We report results on the bioleaching of vanadium, demonstrating the potential for vanadium biomining in the gravity regimes prevailing on asteroids and Mars. The data advance beyond our former results showing biomining of rare earth elements in space ( Cockell et al, 2020 ), and demonstrate the general principles of the biological sequestration of metal ions in bioremediation and recycling efforts beyond Earth.…”

“…have previously been shown to be capable of bioleaching activity such as dissolving insoluble phosphate by chelation ( Senoo et al, 1996 , Teng et al, 2013 ). In bioleaching, S. desiccabilis was also demonstrated to preferentially leach heavy (Gd to Lu) rare earth elements (REEs) over light (La to Eu) REEs ( Cockell et al, 2020 ).…”

“…Its elemental composition, including vanadium content, was determined by ICP-MS (inductively coupled plasma mass spectrometry), and bulk composition was determined by X-ray Fluorescence (XRF). Composition of the rock was previously reported elsewhere ( Cockell et al, 2020 ). Vanadium content is reported here.…”

Graphene Coating as an Effective Barrier to Prevent Bacteria-Mediated Dissolution of Gold

“…It has reported the dissolution of gold by C. metallidurans in various envi- In the case of uncoated Au samples, the interaction between the metallophilic bacteria and Au samples caused a significant surface transformation, with nanoparticulated structures extended all over the surface and a maximum roughness value of 34 nm (See Figure S2). It has reported the dissolution of gold by C. metallidurans in various environments [30,31], followed by the precipitation and biomineralization of Au via the formation of intra and extra-cellular spherical nanoparticles [64,83,84]. Generation of Au-complexing ligands such as organic acids, thiosulfate and cyanide by C. metallidurans biofilms are claimed to be responsible of Au solubilization [31].…”

“…Bioleaching, on the other hand, corresponds to the direct or indirect dissolution of metals from their mineral source by specific microorganisms [28]. Gold is not inert to the presence of key metallophilic bacteria that cause gold bioleaching, such as Chromobacterium violaceum [29], Cupriavidus metallidurans [30,31] and Pseudomonas fluorescens [32]. This biochemical process has been successfully applied for metal extraction and recovery worldwide [33,34].…”