Rare earth element-dependent microbial growth and biomining potential in Methylobacterium fujisawaense LAC1.

Rare earth elements (REEs) are essential for modern technology and have recently been recognized for their role in microbial methanol oxidation, particularly in methanotrophs and methylotrophs. We report a novel acidophilic methylotroph, Methylobacterium fujisawaense LAC1 that exhibits a remarkable ability to utilize and accumulate both light and heavy REEs. This is the first methylotroph reported to utilize and accumulate heavy REEs. Strain LAC1 can grow on acetate, glycerol, succinate, 1-butanol, glucose, and dodecane with calcium. Specifically, with certain REEs, LAC1 can also metabolize ethanol, 1-propanol, 2-propanol, and octane. The ability of LAC1 to use a wide variety of C2 - C12 compounds exceeds that of the ability of reported facultative methylotrophs (C2-C6). Genome analysis revealed homologs of REE-dependent alcohol dehydrogenases (xoxF1, xoxF2, exaF, PedH) and the PQQ-dependent glucose dehydrogenase (GDH). When cultivated with both lanthanum (La) and Ytterbium (Yb), methanol-grown LAC1 shows no change in their accumulation, suggesting distinct mechanisms exist for light REE and heavy REE uptake and accumulation. The strain can also extract REEs from cigarette lighter flints for growth, accumulate the REEs, and thrive at a low pH of 3. All these findings suggest that strain LAC1 is ideal for sustainable REE biomining.