High-yield magnetosome production of Magnetospirillum magneticum strain AMB-1 in flask fermentation through simplified processing and optimized iron supplementation.

Objectives: Developing a simplified flask fermentation strategy utilizing magnetotactic bacterium AMB-1 and optimized iron supplementation for high-yield magnetosome production to address the challenges associated with magnetosome acquisition.

Results: A reliable processing for the pure culture of AMB-1 was established using standard laboratory consumables and equipment. Subsequently, the medium and iron supplementation were optimized to enhance the yield of AMB-1 magnetosomes. The mSLM supported higher biomass accumulation in flask fermentation, reaching an OD₅₆₅ of ~ 0.7. The premixed solution of ferric quinate and EDTA-Fe (at a ratio of 0.5:0.5 and a concentration of 0.4 mmol/L) stabilized Fe³⁺ and significantly increased the reductase activity of AMB-1. Flask fermentations with an initial volume of 15 L were then conducted employing the optimized fermentation strategy. After two rounds of iron and nutrient supplementation, the magnetosome yield reached 185.7 ± 9.5 mg/batch (approximately 12 mg/L), representing the highest AMB-1 flask fermentation yield to our knowledge.

Conclusion: A flask fermentation strategy for high-yield magnetsome production was developed, eliminating the need for bioreactors and greatly simplifying the process of magnetosome acquisition.