Trans-cinnamaldehyde inhibits Escherichia coligrowth by regulating lipopolysaccharide accumulation

Colibacillosis is among the most commonly occurring and economically devastating bacterial diseases of poultry worldwide owing to the misuse and overuse of antibiotics. Trans-cinnamaldehyde exhibits effective inhibition on multidrug-resistant Escherichia coliby disrupting the integrity of its cell wall. However, the mechanism underlying this inhibition is unclear. We found that trans-cinnamaldehyde inhibited E. coliefficiently with a minimum inhibitory concentration (MIC) of 140 μg/mL. Trans-cinnamaldehyde disrupted the integrity of the E. colicell wall due to an imbalance between lipopolysaccharide (LPS) and phospholipids. The structural change in the cell wall disrupted its stability, further causing the leakage of alkaline phosphatase (AKP) and β-galactosidase, proteins, and DNA/RNA, and altering biofilms in the E. coliCVCC 1567 and the E. coli(047). This finally resulted in the death of E. coli.Inhibition by trans-cinnamaldehyde was more significant on the wall of E. coliCVCC 1567 because of a more severe loss of high molecular weight proteins and an easier dissolution of its cells. Trans-cinnamaldehyde affected gene expression of enzymes regulating LPS synthesis (lpxC, lpxA, lpxK, lpxM, yejM, ftsH, lapB), ultimately altering (LPS) content. Indeed, this effect is particularly pronounced in the genes expression of E. coli(047). In conclusion, trans-cinnamaldehyde is a potential novel drug candidate for preventing and treating infectious diseases caused by resistant E. coliclinical strains.