Investigation of specific interactions between microbial cells and polyclonal antibodies using a resonator with lateral electric field

The interaction between polyclonal antibodies and Azospirillum brasilense Sp7 cells was studied using a resonator with lateral electric field. To this end, specific polyclonal rabbit antibodies against the O-antigen epitopes of the strain A. brasilense Sp7 were obtained and the possibility of their application for detection of microbial cells using a piezoelectric resonator with lateral electric field was shown. It was established that frequency dependences of the real and imaginary parts of electrical impedance of such a resonator loaded with the suspension of A. brasilense Sp7 cells and antibodies substantially differed from those of the resonator with the control suspension of cells without antibodies. It was shown that the obtained antibodies interacted with azospirilla cells, and the marker was accumulated all over the cell surface. The limit of possible detection of microbial cells during their interaction with antibodies was found to be 104 cells/mL. Detection of A. brasilense Sp7 cells using antibodies proved to be possible in the presence of foreign bacteria. The presented results demonstrate the possibility of recording the interaction between microbial cells and antibodies and developing a biosensor for quantitative detection of microbial cells.