Electrophoretic Determination of Lactococcus lactis Modified by Zinc Ions

Abstract

The developed capillary electrophoresis (CE) method was applied to evaluate the aggregation activity of divalent metal ions (zinc) on bacterial cells. In our study, the influence of the Lactococcus lactis surface modification by zinc ions at different concentration (1, 3 and 10 mM, respectively) was determined. Electrophoretic results in pseudo isotachophoretic mode indicated that using a Zn aq2+ caused the uncontrolled aggregation of bacterial cells and, as a result, new signals of microbial agglomerates were observed in the electropherogram. Moreover, the observed process is strongly related with the concentration of the used Zn aq2+ solution—the number of bacterial agglomerates increased with an increasing concentration of modifier. The phenomenon of L. lactis uncontrolled clumping was also evaluated by application of size distribution and spectrometric in infrared range measurements (FT-IR) measurements. The obtained data indicated that the main groups involved in the bacterial cells aggregation process are deprotonated carboxyl and amid groups derived from microbial surface proteins. As a consequence, the proposed mechanism of the L. lactis uncontrolled clumping process is presented. In addition, data from fluorescence microscopy pointed out damage cells analyzed direct after electroanalysis. Therefore, CE may be a potential method for evaluating the aggregation activity of different types of bivalent metal ions against microbial cells.