The E. coli O55:B5 LPS (Sigma–Aldrich Japan), the LPSs extracted from Acinetobacter lwoffii JCM 6840, the river water, and the BAC effluent samples (5000 EU/mL) were pretreated with 50 μg/mL polymixin B sulphate (Sigma Aldrich Japan) for 1 h at room temperature.