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Isolation of salmonellas by immunomagnetic separation
A E Vermunt1, A A Franken, R R Beumer
1State Institute for Quality Control of Agricultural Products (RIKILT-DLO), Wageningen, The Netherlands.
The Journal of Applied Bacteriology
|February 1, 1992
Summary
This study developed an immunomagnetic separation method to isolate Salmonella livingstone. Using skim milk instead of bovine serum albumin significantly reduced non-specific reactions, improving Salmonella isolation from food samples.
Area of Science:
- Microbiology
- Immunology
- Food Safety
Background:
- Salmonella is a significant foodborne pathogen.
- Accurate isolation of Salmonella from food is crucial for public health.
- Existing isolation methods can be affected by non-specific reactions.
Purpose of the Study:
- To develop and optimize an immunomagnetic separation (IMS) method for isolating Salmonella livingstone.
- To reduce non-specific binding and improve the specificity of IMS for Salmonella detection in food samples.
- To evaluate the efficiency of IMS using different blocking agents.
Main Methods:
- Utilized magnetisable particles coated with anti-Salmonella serum for isolating Salmonella livingstone.
- Incubated beads with bacterial cultures and food samples under specific conditions.
- Tested phosphate-buffered saline (PBS) with bovine serum albumin (BSA) and Tween 20, and later with skim milk, as incubation and washing media.
- Assessed recovery rates for Salmonella livingstone and interfering microorganisms like Aeromonas hydrophila.
Main Results:
- The initial IMS method achieved a Salmonella livingstone recovery of 51.0 +/- 7.8%.
- Non-specific reactions with Aeromonas hydrophila (50.9 +/- 12.7% recovery) interfered with the test.
- Replacing BSA with 4% skim milk in the incubation medium significantly decreased non-specific reactions.
- The ratio of Salmonella livingstone to Aer. hydrophila recovery improved from 0.9 to 13.4 with skim milk.
Conclusions:
- Immunomagnetic separation is a promising technique for concentrating Salmonella spp. from complex bacterial mixtures in food samples.
- The use of skim milk as a blocking agent effectively minimizes non-specific binding, enhancing the specificity of IMS for Salmonella detection.
- Optimized IMS offers improved prospects for the reliable isolation and detection of Salmonella in food safety applications.