Sphingolipid-mediated vesiculation in multidrug-resistant <i>Sphingobacterium detergens</i> under polymyxin B stress

Environmental bacteria often display antibiotic tolerance without carrying canonical resistance genes. We show that <i>Sphingobacterium</i> exploits sphingolipid-dependent outer membrane vesiculation as a structural defense against polymyxin B. Blocking sphingolipid biosynthesis with myriocin suppressed vesiculation and sensitized cells to polymyxin B, indicating that these rare bacterial lipids provide essential sites for drug interaction and membrane remodeling. Our findings reveal a lipid-driven mechanism of vesiculation and highlight sphingolipid metabolism as a potential therapeutic target.