Deletion of major shell proteins of ethanolamine utilization microcompartment reduces intrinsic antibiotic resistance, biofilm, and intracellular survival of Salmonella Typhimurium.

With the high rise in Salmonella infections and emergence of antibiotic resistance, developing a novel strategy to control the pathogen is imperative. Earlier studies have revealed that ethanolamine (EA) metabolism plays a crucial role in Salmonella intestinal colonization; however, the potential of this metabolism as a therapeutic target remains unexplored. The EA metabolic enzymes are localized within a proteinaceous microcompartment (MCP) shell composed of thousands of copies of shell proteins encoded by five genes from the eut operon. Our study reveals that supplementation of EA and vitamin B₁₂ in both rich and minimal media enhances biofilm formation, motility, and tolerance to antibiotics. Conversely, mutants deficient in EA metabolism due to defective MCP shell exhibited no physiological fitness. Fascinatingly, these mutants exhibited enhanced susceptibility to various antibiotics and lower expression of biofilm and curli. Also, a mutation in one of the major shell proteins reduced intramacrophage viability of Salmonella. Notably, phenotypes were restored upon ectopic expression of corresponding genes. Mutations in the MCP shell proteins downregulated the expression of genes related to pathogenicity. Overall, this study sheds new light on understanding the relationship between EA metabolism and bacterial physiology that would pave the way for developing novel therapeutic interventions against Salmonella.