Isolation and Purification of Magnetosomes from Magnetospirillum spp

Magnetotactic bacteria (MTB) produce intracellular magnetic organelles known as magnetosomes, which consist of magnetite or greigite crystals surrounded by a phospholipid membrane. Their uniform nanoscale dimensions, magnetic properties, and membrane-associated proteins make magnetosomes attractive for applications in biotechnology and biomedicine. This protocol describes two complementary methods for isolating and purifying magnetosomes from Magnetospirillum spp., using either probe sonication or high-pressure homogenization (HPH) for cell disruption. Sonication is readily accessible and suitable for small-scale preparations, whereas HPH enables more rapid processing of larger sample volumes. Following cell harvesting and disruption, magnetosomes are recovered using a strong permanent magnet and repeatedly washed to remove residual cellular debris. The workflow is designed to preserve intact magnetosome chains and their surrounding membrane while avoiding specialized purification equipment such as magnetic separation columns or density-gradient ultracentrifugation. Using Magnetospirillum gryphiswaldense MSR-1 as a representative strain, both disruption approaches produced efficient cell lysis and reproducible magnetosome recovery. A 2 L culture grown to an OD600 of approximately 0.4 typically yielded about 40 mg of wet magnetosome material after purification. Once bacterial cultures are available, the complete isolation and purification workflow can be completed within approximately 8 h.