Research Article Open Access

Development of an Immunomagnetic Separation Method for Viable Salmonella Typhimurium Detected by Flow Cytometry

Shakil Ahmed1, Horst-Günter Rubahn2 and Helmut Erdmann1
  • 1 Flensburg University of Applied Sciences, Germany
  • 2 University of Southern Denmark, Denmark


A very small number of bacterial pathogens may have fatal effects on food safety. In spite of having great advancements in bioanalytical methods, most of the accepted detection methods are still cultivation based and thus time consuming. This leads to an intense need for efficient and rapid methods for detection of food-related bacteria. In this study, a flow cytometry based immunomagnetic separation (IMS) method for the isolation and enrichment of Salmonella Typhimurium from liquid samples was developed and optimized. Both polyclonal and monoclonal antibodies have been used to couple with 1 micron sized paramagnetic particles for the preparation of immunomagnetic beads (IMBs). The most suitable antibody was chosen by applying an enzyme linked immunosorbent assay (ELISA), whereas living bacteria were detected by flow cytometry. The parameters for both IMS and flow cytometry e.g., concentration of bead and bacteria, immunocapture time, staining and buffering conditions for the viability assays were optimized. The capture efficiency of IMS was>98% for a range of Salmonella Typhimurium cell concentrations from 103 to 105/mL using 108/mL bead concentration. The method proved to have high (98%) specificity towards Salmonella Typhimurium and very low (< 5%) binding with non-target bacterial strains.

OnLine Journal of Biological Sciences
Volume 16 No. 4, 2016, 165-174


Submitted On: 15 September 2016 Published On: 25 November 2016

How to Cite: Ahmed, S., Rubahn, H. & Erdmann, H. (2016). Development of an Immunomagnetic Separation Method for Viable Salmonella Typhimurium Detected by Flow Cytometry. OnLine Journal of Biological Sciences, 16(4), 165-174.

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  • Immunomagnetic Separation
  • Lab-on-a-Chip
  • Flow Cytometry
  • Salmonella Typhimurium