Electrophysical sensor systems for in vitro monitoring of bacterial metabolic activity

Intense use of microbial cells in biotechnological production requires rapid methods to monitor bacterial growth online and analyze the regulation of microbial metabolic activity. Some details of metabolic activity are examined conventionally, by changing the concentration of nutrient medium components, the concentration of metabolites, the pH, the respiratory activity, and other variables. In this case, the set of variables used may turn out insufficient and a number of critical points of the control process will remain in the shadow. The enzymatic catalysis in the bacterial cell is accompanied by a redistribution of charges inside the cell and, therefore, may lead to a change in its electrophysical characteristics. Ideally, researchers should use structurally intact and metabolically undisturbed growing cells to fully understand the enzymatic processes in microbes. Electrophysical analysis, based on the study of cells as electrophysical objects and on the measurement of their polarization characteristics, is a new approach to assessing the intravital physiological variables of cells and their heterogeneity. This article describes the theoretical principles of electrophysical analysis of bacteria and shows the possibilities of methods for examining the metabolic status of bacteria.