Methylobacterium REE E-waste Platform

An engineered monoculture bioplatform based on the mesophilic methylotrophic bacterium Methylobacterium extorquens AM1 for sustainable recovery of rare earth elements (REE) from electronic waste. This system represents a paradigm shift in critical materials recovery through non-acidic, green bioprocessing that eliminates the harsh chemical leaching typical of conventional REE extraction. M. extorquens naturally accumulates REE in intracellular polyphosphate granules during methanol metabolism, achieving baseline bioaccumulation of 3.2 mg Nd/g dry cell weight. Through metabolic engineering—overexpression of lanthanophore biosynthesis genes (mll operon under lac promoter control) and deletion of exopolyphosphatase (ppx)—REE bioaccumulation was enhanced to 202 mg Nd/g DCW (63-fold improvement), representing one of the highest microbial REE loading capacities reported. The platform achieves remarkable selectivity with 98% of accumulated metal being REE and 96.8% of that being neodymium, critical for permanent magnet recycling. The system operates at near-neutral pH (6.9), mesophilic temperature (29-30°C), and scales to 10-liter bioreactors with controlled organic acid supplementation (5-15 mM citrate). After bioleaching with citrate, 58.7 ppm REE are mobilized from electronic waste (magnet swarf), followed by cellular bioaccumulation and recovery. This consolidated platform integrates leaching, bioaccumulation, and recovery in a single organism, offering environmental advantages over acidic chemical processing while addressing circular economy needs for critical materials in clean energy technologies.