Bunin V.D., Ignatov O.V., Guliy O.I., Voloshin A.G.,
Dykman L.A., O’Neil D., Ivnitski D. |
|
Abstract
An electro-optical (EO) approach has been used for studies of Listeria monocytogenes–antibody
binding. The EO analyzer, which has been developed at the State Research Center for Applied
Microbiology, Obolensk, was used as a basic instrument for EO measurements. AC electro-kinetic
effects depend on dielectric properties of bioparticles, their composition, morphology, the
medium, and the frequency of applied electrical field. Electro-orientational spectra were used for
discrimination of bacteria before and after selective binding with antibodies. The measurements
were performed using a discrete set of frequencies of the orienting electric field (10, 100, 250,
and 500 kHz). During biospecific interactions an antibody is bound to the microorganism causing a
change in the dielectric properties of the microorganism–antibody complex and the EO signal
reaches its maximum at 100–200 kHz. It has been shown that the biospecific interactions of L.
monocytogenes cells with anti-Listeria antibody in the presence of Escherichia coli K-12, and
Azospirillum brasilense Sp7 change the EO signals significantly. Thus, the determination of the
presence of particular bacteria within a mixed sample may be achieved by selection and matching of
antibodies specific to individual bacterium types and by comparing spectra of bacterium in the
presence and in the absence of specific antibody. |
