FIG 3.

IBG exerts bactericidal activity by interacting with cytoplasmic membrane. (A) The antibacterial activity of IBG combined with phosphatidylglycerol (PG), phosphatidylethanolamine (PE), or cardiolipin (CA) was determined by checkerboard broth microdilution assays. (B) The conformational structure of IBG (10 μg/mL) with or without PG (32 μg/mL) was evaluated by the circular dichroism (CD) spectra. (C) Increased permeability of inner membrane was probed with PI for S. aureus ATCC 29213 treated with different concentrations of IBG. (D) Synergistic activity between IBG and three major membrane phospholipids against the LPS mutant strain MG1655-ΔwaaC was detected, and PG and CA remarkably reduced the antibacterial activity of IBG.