Microbial Co-Accumulation of Indium, Gallium, and Arsenic and Formation of Multicomponent Mineral Precursors under Ambient Conditions

Abstract Group III−V compound semiconductors are essential for electronic and optoelectronic technologies but rely on scarce and toxic elements, necessitating sustainable recovery strategies. Although microorganisms are known to mediate biomineralization of various metal compounds, their ability to form III−V−related phases remains unclear. This study aimed to determine whether microbial consortia can simultaneously accumulate group III (In, Ga) and group V (As) elements and form precursor mineral phases. Marine-derived microbial consortia were enriched in the presence of In3+, Ga3+, and arsenate. Two consortia, IGA-1 and IGA-2, were selected based on their high uptake efficiencies. Mineral formation was analyzed using TEM, EDS, and ICP-OES, and crystallinity was evaluated before and after heat treatment. Both consortia accumulated In, Ga, and As and formed nanoscale mineral particles containing these elements. The particles were predominantly amorphous, although localized lattice fringes were observed within some particles, indicating nanoscale crystalline ordering, although the corresponding crystalline phases could not be identified. Heat treatment at ≥500°C resulted in the formation of crystalline In2O3, accompanied by arsenic loss. These results demonstrate that microbial consortia can co-concentrate group III and V elements and generate multicomponent amorphous precursor materials, highlighting their potential for the biological recovery and preprocessing of semiconductor-related elements.