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Immunomagnetic separation of Erwinia carotovora subsp. atroseptica from potato peel extracts to improve detection sensitivity on a crystal violet pectate medium or by PCR
Author(s) -
van der Wolf J.M.,
Hyman L.J.,
Jones D.A.C.,
Grevesse C.,
Van Beckhoven J.R.C.M.,
Van Vuurde J.W.L.,
Pérombelon M.C.M.
Publication year - 1996
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1996.tb03247.x
Subject(s) - erwinia , bacteria , biology , immunomagnetic separation , microbiology and biotechnology , antiserum , enterobacteriaceae , crystal violet , food science , chemistry , escherichia coli , biochemistry , antibody , genetics , gene , immunology
Immunomagnetic separation (IMS) procedures for the selective separation of Erwinia carotovora subsp. atroseptica from potato peel extract were optimized for the recovery of target and removal of nontarget bacteria. A streptomycin‐resistant strain of Erw. carotovora subsp. atroseptica was used in combination with a crystal violet pectate (CVP) medium supplemented with 100 μg ml −1 of streptomycin to determine the recovery level of the target bacterium. Recovery obtained with a polyclonal antiserum against Erw. carotovora subsp. atroseptica at a concentration of 6 μg IgG ml −1 was greater than that obtained with two monoclonal antibodies against lipopolysaccharides of Erw. carotovora subsp. atroseptica at a concentration of 10 μg IgG ml −1 . A linear relationship was found between particle concentration ranging from 12 to 200 μg ml −1 and recovery level. When the Advanced Magnetics (AM) protein A and anti‐rabbit IgG particles in the AM separation system and the Dynal anti‐rabbit IgG particles in the Dynal separation system were examined, the highest recovery level per μg of particles (66%) was obtained with the Advanced Magnetics protein A particles, followed by AM anti‐rabbit particles (37%). Without IMS, detection of Erw. carotovora subsp. atroseptica in tuber peel extracts on a CVP‐medium without streptomycin was impossible when the ratio of Erw. carotovora subsp. carotovora to Erw. carotovora subsp. atroseptica was greater than 100 or when large numbers of other saprophytic bacteria were present, because of overcrowding. IMS, using the AM anti‐rabbit IgG particles, ensured that Erw. carotovora subsp. atroseptica could be enumerated in tuber peel extract consistently, to a detection level of 100 cells ml −1 . Similarly, the IMS procedure lowered the detection level of Erw. carotovora subsp. atroseptica in a twofold diluted peel extract by PCR to ca 2·0 × 10 3 cells ml −1 or 50 cells per reaction tube. In contrast, positive results in PCR without IMS were obtained only when the peel extract was diluted 100 times and when the concentration of Erw. carotovora subsp. atroseptica was at least 10 5 cells ml −1 .