Presentation Information
[P04-565]Development of an efficient harvesting method for magnetotactic bacteria using high-gradient magnetic separation
Rika Miyata1, ○Iori Hasegawa1, Tadashi Matsunaga1, Tsuyoshi Tanaka1, Atsushi Arakaki1 (1. Department of Biotechnology and Life science, Graduate School of Engineering, Tokyo University of Agriculture and Technology (Japan))
Keywords:
Cell recovery,Magnetic separation,Low-energy process,Microbial bioproduction,Magnetotactic bacteria
[Purpose]In microbial bioproduction, cell recovery remains a significant challenge, accounting for approximately 20–30% of the total production cost. Magnetic separation has been proposed as a low-energy alternative to conventional centrifugation and filtration, yet existing approaches still require significant energy input due to the use of external electromagnets and magnetic particles. In this study, we investigated the applicability of high gradient magnetic separation (HGMS) using permanent magnets for the recovery of magnetotactic bacteria (MTB) with the aim of developing a scalable, low-energy separation system.
[Method]Capture efficiency of cells was first evaluated using a commercial MACS column with a recombinant Magnetospirillum magneticum strain AMB-1 harboring double copies of magnetosome biosynthesis genes. Steel wool was then assessed as an alternative, low-cost column packing material to facilitate large-scale recovery. Finally, a custom magnetic separation device was constructed to generate uniform magnetic flux density throughout the column, and its performance was evaluated using 1 L of high-density culture of the recombinant strain.
[Results]MACS column-based HGMS achieved capture efficiencies of 95% with cell densities ranging from 1.0 to 10 × 107 cells/mL, confirming the suitability of HGMS for MTB recovery. When steel wool was used as the packing material, capture efficiency increased with the amounts of steel wool loaded, reaching a maximum of 94%. Using the custom-built separation device, recovery from 1 L of high-density cultures yielded a capture efficiency of approximately 81%.
[Consideration]These results collectively demonstrate that HGMS is an effective and scalable strategy for MTB recovery. The use of steel wool, a low-cost ferromagnetic material with a high specific surface area, enabled efficient magnetic capture without the need for external labelling agents. Liter-scale performance further supports the potential of this system as a primary concentration step in downstream bioprocessing. The introduction of magnetosome synthesis genes into industrially relevant microorganisms could broaden the applicability of this approach to recovery of diverse bioproducts.
[Conclusion]A steel wool-based HGMS system achieved a capture efficiency of 94% for MTB and 81% at the liter scale. This approach offers a low-energy, scalable alternative for cell recovery in microbial bioproduction, and its potential extension to other microorganisms via magnetosome gene introduction warrants further investigation.
[Method]Capture efficiency of cells was first evaluated using a commercial MACS column with a recombinant Magnetospirillum magneticum strain AMB-1 harboring double copies of magnetosome biosynthesis genes. Steel wool was then assessed as an alternative, low-cost column packing material to facilitate large-scale recovery. Finally, a custom magnetic separation device was constructed to generate uniform magnetic flux density throughout the column, and its performance was evaluated using 1 L of high-density culture of the recombinant strain.
[Results]MACS column-based HGMS achieved capture efficiencies of 95% with cell densities ranging from 1.0 to 10 × 107 cells/mL, confirming the suitability of HGMS for MTB recovery. When steel wool was used as the packing material, capture efficiency increased with the amounts of steel wool loaded, reaching a maximum of 94%. Using the custom-built separation device, recovery from 1 L of high-density cultures yielded a capture efficiency of approximately 81%.
[Consideration]These results collectively demonstrate that HGMS is an effective and scalable strategy for MTB recovery. The use of steel wool, a low-cost ferromagnetic material with a high specific surface area, enabled efficient magnetic capture without the need for external labelling agents. Liter-scale performance further supports the potential of this system as a primary concentration step in downstream bioprocessing. The introduction of magnetosome synthesis genes into industrially relevant microorganisms could broaden the applicability of this approach to recovery of diverse bioproducts.
[Conclusion]A steel wool-based HGMS system achieved a capture efficiency of 94% for MTB and 81% at the liter scale. This approach offers a low-energy, scalable alternative for cell recovery in microbial bioproduction, and its potential extension to other microorganisms via magnetosome gene introduction warrants further investigation.
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