In order to identify pathogens rapidly and reliably, it is often required to capture and concentrate them from large sample volumes into smaller ones. Magnetic labeling and capture of bacteria using a magnetic field holds great promise towards achieving this goal, but current protocols suffer from poor capture efficiency. Here, we present a rapid and highly efficient approach to magnetic labeling and capture of both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria using cationized magnetoferritin (cat- MF). Magnetic labeling was achieved within a one minute incubation period with cat-MF, and 99.97% of the labeled bacteria could be immobilized in commercially available magnetic cell separation (MACS) columns. Longer incubation times led to more efficient capture, with S. aureus being immobilized to a greater extent than E. coli. Finally, low numbers of magnetically labeled E. coli (< 100 colony forming units per mL) were immobilized with 100% efficiency and concentrated 7-fold within 15 minutes. Therefore, our study provides a novel protocol for rapid and highly efficient magnetic labeling, capture and concentration of both Gram-positive and Gram-negative bacteria.
Correia Carreira, S., Spencer, J., Schwarzacher, W., & Seddon, A. (2016). Cationized magnetoferritin enables rapid labeling and concentration of Gram-positive and Gram-negative bacteria in magnetic cell separation columns. Applied and Environmental Microbiology, 82(12), 3599-3604. https://doi.org/10.1128/AEM.00720-16