GNPS - Untargeted Metabolomics and Lipidomics Reveal Complex Pathways Spurred by Activation of Acid Resistance Mechanisms in Escherichia coli

Escherichia coli (E. coli) is a ubiquitous group of bacteria that can be either commensal gut microbes or enterohemorrhagic food-borne pathogens. Regardless, both forms must survive acidic environments in the stomach and intestines to reach and colonize the gut, a process that partially relies on amino acid dependent acid resistance (AR) mechanisms and modifications to membrane phospholipids. However, only the basic tenets of these mechanisms have been elucidated. In this paper, we aim to conduct the first known full-scale metabolic and lipidomic characterization of E. coli adaptations to acid stress. We hypothesized that the use of untargeted metabolomics and lipidomics would reveal mechanisms downstream of AR processes that provide novel contributions to acid stress survival. We detected significant differences in the extracellular metabolome and the lipidome induced by amino acid supplementation (glutamine, arginine, or lysine) and contextualized these results using RT-qPCR. We additionally identified distinct metabolic and lipidomic pathways modulated by differential amino acid supplementation. These results demonstrate AR may not be simply a set of basic mechanisms but rather a coordinated acid resistant metabolic phenotype. Future studies may use our analysis to elucidate distinct targets for prebiotic supplements to cultivate commensal strains or therapies to combat pathogenic ones.