Metabolic adaptations of Escherichia coli to extended zinc exposure: Insights into tricarboxylic acid cycle and trehalose synthesis

Balanced bacterial metabolism is essential for cell homeostasis and growth and can be impacted by various stress factors. In this study, we investigated the impact of extended exposure of Escherichia coli to zinc oxide (ZnO40) and zinc oxide nanoparticles (ZnONPs40) on the major metabolic pathways of E. coli with the aim to simulate long-term stress conditions. Transcriptomic and proteomic analyses along with quantification of intermediates of tricarboxylic acid (TCA) were employed to monitor and study the bacterial responses. Multi-omics analysis revealed that extended zinc exposure induced mainly oxidative stress and elevated expression/production of enzymes of carbohydrate metabolism, especially enzymes for synthesis of trehalose. After the zinc withdrawal, E. coli metabolism returned to a baseline state. These findings shed light on the alteration of TCA and on importance of trehalose synthesis in metal-induced stress and its broader implications for bacterial metabolism and defense.