Comparison of ATP and in vivo bioluminescence for assessing the efficiency of immunomagnetic sorbents for live Escherichia coli O157:H7 cells.
OBJECTIVE
To develop methods to assess the efficiency of immunomagnetic separation (IMS).


RESULTS
The capturing efficiency of biosorbents for Escherichia coli O157:H7, constructed using streptavidin-coated magnetic beads and biotinylated antibodies, was tested using both in vivo and ATP bioluminescence. Both methods were suitable for the enumeration of bacteria captured by the biosorbents. The level of both ATP and in vivo bioluminescence depended on the media used, but was unaffected by the magnetic beads. The capture efficiency depended on time and sample volume, but did not depend on the length of spacer arm of the biotinylation agent. For cell concentrations of <or= 105 cfu ml-1, in a 1-ml sample volume, nearly 80-85% recovery of the pathogen was observed after 0.5 h of incubation. For an 11-ml sample containing 104 cfu ml-1, maximum recovery (50% of cells) was achieved only after 2 h incubation.


CONCLUSIONS
The detection limit of an ATP-based bioluminescent assay for E. coli O157:H7 was reduced by 1 log cycle after optimization of IMS. The bioluminescent methods could be used for screening and testing the affinity of antibodies or other affinity elements of biosorbents towards live bacterial cells.


CONCLUSIONS
Bioluminescent assays provide an easy way to optimize conditions for the capture of bacteria by biosorbents in real time.
Sun
W
W
Department of Food Science, University of Guelph, Guelph, Canada.
Khosravi
F
F
Albrechtsen
H
H
Brovko
L Y
LY
Griffiths
M W
MW
D000255:Adenosine Triphosphate / Q000032:analysis*; D015169:Colony Count, Microbial; D003470:Culture Media; D019453:Escherichia coli O157 / Q000302:isolation & purification* / Q000648:ultrastructure; D005516:Food Microbiology; D018189:Immunomagnetic Separation / Q000379:methods*; D007163:Immunosorbent Techniques; D008163:Luminescent Measurements; D008855:Microscopy, Electron, Scanning
D003470:Culture Media; D000255:Adenosine Triphosphate