Life Cycle Analysis of Magnetosome Biomanufacturing

Abstract Production of iron oxide magnetic nanoparticles using conventional chemical and physical methods presents sustainability challenges due to often high energy consumption and the use of hazardous reagents. Biological synthesis via magnetotactic bacteria (MTB) offers a greener alternative, but its environmental performance remains unexplored at scale. This study addresses this gap by conducting a life cycle assessment (LCA) of magnetosome production and purification, using a ‘cradle-to-gate’ approach. Key findings identified environmental hotspots in both upstream and downstream processing, in particular, bioreactor fermentation and magnetically enhanced density separation (MEDS). MEDS showed the highest environmental burden, accounting for 61% of global warming potential (GWP), 70.6% of terrestrial ecotoxicity, 74.6% of marine eutrophication, and 91% of land use, primarily due to its reliance on the specialty surfactant, Eumulgin ES. Notably, the bioreactor unit accounted for 53.7% of water consumption, 52.4% of human non-carcinogenic toxicity, 38.0% of fossil resource scarcity, and 33% of the total GWP, driven by the requirements for bacterial culture media and energy inputs to maintain optimal temperature for bacterial growth. This study shows that recovering protein and PHA as co-products modestly improved environmental impact metrics (below 0.75%), while enabling process circularity. The sensitivity analysis revealed that increasing cellular iron uptake from 33.1 to 300 mg of iron per gram of dried cell weight (mg Fe g–1 DCW) could reduce environmental impacts by >10.4-fold, while raising the rotor-stator high-gradient magnetic separation (RS-HGMS) yield from 70 to 99% could reduce emissions by 1.4-fold.