Skip to main content
Applied and Environmental Microbiology logoLink to Applied and Environmental Microbiology
. 1997 May;63(5):1643–1646. doi: 10.1128/aem.63.5.1643-1646.1997

Immunomagnetic detection of Bacillus stearothermophilus spores in food and environmental samples.

M R Blake 1, B C Weimer 1
PMCID: PMC168457  PMID: 9143097

Abstract

There are currently no methods for the rapid and sensitive detection of bacterial spores that could be used to direct raw materials containing high spore loads away from products that pose a food safety risk. Existing methods require an overnight incubation, cannot detect spores below 10(5) CFU/ml, or are not specific to particular species. This work describes a method to specifically detect < 10(4) CFU of bacterial spores per ml within 2 h. Polyclonal antibodies to Bacillus stearothermophilus spores were attached to 2.8-micron-diameter magnetic polystyrene beads by using a polythreonine cross-linker via the antibody carbohydrate moiety. A biotin-avidin-amplified sandwich enzyme-linked immunosorbent assay coupled to a fluorescent substrate was used to quantitate captured spores. The concentration of B. stearothermophilus spores in samples was linearly correlated to fluorescent activity (r2 = 0.99) with a lower detection limit of 8 x 10(3) CFU/ml and an upper detection limit of 8 x 10(5) CFU/ml. The detection limits are not fixed and can be changed by varying the immunomagnetic bead concentration. Several food and environmental samples were tested to demonstrate the versatility of the assay.

Full Text

The Full Text of this article is available as a PDF (285.7 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bruno J. G., Yu H. Immunomagnetic-Electrochemiluminescent Detection of Bacillus anthracis Spores in Soil Matrices. Appl Environ Microbiol. 1996 Sep;62(9):3474–3476. doi: 10.1128/aem.62.9.3474-3476.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Du C., Nickerson K. W. Bacillus thuringiensis HD-73 Spores Have Surface-Localized Cry1Ac Toxin: Physiological and Pathogenic Consequences. Appl Environ Microbiol. 1996 Oct;62(10):3722–3726. doi: 10.1128/aem.62.10.3722-3726.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Gombas D. E., Gomez R. F. Sensitization of Clostridium perfringens spores to heat by gamma radiation. Appl Environ Microbiol. 1978 Sep;36(3):403–407. doi: 10.1128/aem.36.3.403-407.1978. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Hofstra H., van der Vossen J. M., van der Plas J. Microbes in food processing technology. FEMS Microbiol Rev. 1994 Oct;15(2-3):175–183. doi: 10.1111/j.1574-6976.1994.tb00133.x. [DOI] [PubMed] [Google Scholar]
  5. Kricka L. J. Selected strategies for improving sensitivity and reliability of immunoassays. Clin Chem. 1994 Mar;40(3):347–357. [PubMed] [Google Scholar]
  6. Krusell L., Skovgaard N. Evaluation of a new semi-automated screening method for the detection of Salmonella in foods within 24 h. Int J Food Microbiol. 1993 Nov 26;20(3):123–130. doi: 10.1016/0168-1605(93)90105-p. [DOI] [PubMed] [Google Scholar]
  7. Lund A., Hellemann A. L., Vartdal F. Rapid isolation of K88+ Escherichia coli by using immunomagnetic particles. J Clin Microbiol. 1988 Dec;26(12):2572–2575. doi: 10.1128/jcm.26.12.2572-2575.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Morgan J. A., Winstanley C., Pickup R. W., Saunders J. R. Rapid Immunocapture of Pseudomonas putida Cells from Lake Water by Using Bacterial Flagella. Appl Environ Microbiol. 1991 Feb;57(2):503–509. doi: 10.1128/aem.57.2.503-509.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Skjerve E., Olsvik O. Immunomagnetic separation of Salmonella from foods. Int J Food Microbiol. 1991 Oct;14(1):11–17. doi: 10.1016/0168-1605(91)90032-k. [DOI] [PubMed] [Google Scholar]
  10. Skjerve E., Rørvik L. M., Olsvik O. Detection of Listeria monocytogenes in foods by immunomagnetic separation. Appl Environ Microbiol. 1990 Nov;56(11):3478–3481. doi: 10.1128/aem.56.11.3478-3481.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Wright D. J., Chapman P. A., Siddons C. A. Immunomagnetic separation as a sensitive method for isolating Escherichia coli O157 from food samples. Epidemiol Infect. 1994 Aug;113(1):31–39. doi: 10.1017/s0950268800051438. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Applied and Environmental Microbiology are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES