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

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 rng/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. (C) 2017 Elsevier Ltd. All rights reserved.