Antibacterial activity and mechanism of B-type oligomeric procyanidins from lotus seedpod on enterotoxigenic Escherichia coli

- LSPC showed high antibacterial activity on ETEC strains in a dose-dependent manner.
- The mechanism of LSPC against ETEC was by disturbing cell membrane structure and function.
- LSPC promoted the growth of the beneficial bacteria even at high concentration.
- LSPC could be a potential natural agent to reduce or prevent the ETEC related gut disease.

This study aims to evaluate the antimicrobial activity and mechanism of B-type oligomeric procyanidins from lotus seedpod (LSPC) against two Enterotoxigenic Escherichia coli (ETEC) strains, and the effects of LSPC on the growth of six different beneficial bacteria were also investigated. The antimicrobial activity assay showed LSPC exerted its action on ETEC strains in a dose-manner, in which the growth of ETEC strains were promoted at low concentration but inhibited at the concentration higher than 0.8 mg/mL and 1.2 mg/mL respectively. In comparison, the tolerance of beneficial bacteria on LSPC was significant higher than ETEC strains, LSPC promoted the growth of 5 Lactobacillus strains at the concentration of 0.8 mg/mL. Cell morphology, cell permeability and cell integrity assays suggested that the mechanism of LSPC against ETEC strains was by disturbing cell membrane structure and function. The current results demonstrated the potential benefit of LSPC to the gut microbial regulation.