Nitroaromatic Compounds Dictate Electrochemical Properties of Escherichia coli by Manipulating the Cellular Membrane.

Abstract

Nitroaromatic compounds (NACs) are generally used as starting materials and/or generated as byproducts during the manufacturing of dyes, fertilizers, and therapeutic agents. Though NACs are beneficial when used appropriately, inadequate management, disposal, and application methods have led to their introduction to bacterial ecosystems where NACs act as mutagenic agents and may even contribute to antimicrobial resistance. Many of these bacterial systems are known to have different pathways to adapt to the presence of NACs such as altering the lipid composition of cellular membranes and intracellular degradation of NACs. In general, these processes require sophisticated techniques and skilled human resources to detect the changes by conventional characterization techniques. Hence, alternative methods are needed to investigate the short-term effects of NACs on bacterial cells with better precision. Herein, we report that bacterial cells adapt to the presence of NACs initially by incorporation in the cellular membrane, which can be predicted by further altered electrical and electrochemical properties of the cells. It was observed that the whole cell bacteria were negatively charged entities that could generate varying levels of surface charges on being incubated with model NACs of biomedical importance viz. niclosamide and p-nitrophenol. Such variations were also reflected in dye entrapment assays performed by using lipidic membranes collected from NAC-treated bacterial cells after the cells. Further studies with gel electrophoresis and differential pulse voltammetry revealed the significant alterations in electrochemical properties of NAC-incubated bacterial cells. Overall, results indicate that bacterial adaptation to NACs was found to be closely linked to variations in the electrochemical properties of the bacterial cells. These outcomes advance our understanding of influences imparted by NACs during bacterial infections and might facilitate the way for developing therapies to combat antibacterial resistance in the near future.