Integrated proteomic analysis reveals physiological changes during cometabolic degradation of Tetrabromobisphenol A (TBBPA) by Enterobacter cloacae strain ECsp1

Using labelled-free proteomics, this study elucidates that the Enterobacter cloacae ECsp1 strain's response to tetrabromobisphenol A (TBBPA) exposure, revealing the degradation of the compound via cometabolism, which remodels the bacterial proteome. TBBPA is the dominant brominated flame retardant worldwide, but its degradation in wastewater plants remains poorly understood. Among the 531 identified proteins, 43 were up-regulated and 23 were down-regulated. Overexpressed proteins indicate that exposing this microorganism to the toxicant involves both up- and downregulation of enzymes involved in carbohydrate metabolism, genetic information processing, biosynthesis, cell maintenance, and xenobiotic degradation pathways. Evaluating the variation in protein abundance suggests degradation pathways related to: 1) the final steps of the glycolysis and alcohol fermentation in a cometabolism with glucose by phosphoglycerate mutase (PPM) and alcohol dehydrogenase (ADH) and 2) cleavage of the aromatic ring by carboxymuconolactone decarboxylase (CMD), specifically targeting benzoate and phenolic groups. The group of enzymes showing the widest variety of significantly upregulated proteins is related to xenobiotic transport elements (ABC transporters). Additionally, oxidative stress and envelope stress response are suggested by the upregulation of peroxidases and NlpE enzymes. Understanding dynamic changes in the protein expression sheds light on the metabolic mechanisms underlying TBBPA degradation during acidogenesis.