On-column E. coli infection. Two phage libraries, L6 and L15, were used for column panning and on-column infection. Two rounds were performed as described in Table 1. As a reference sample, a single phage clone HuN, was used for on-column infection. The binding efficiency was determined using HuLF ELISA as described in Material and Methods. (a) On-column cell infection on a HuLF column with the HuN single-phage clone. HuN phage reference sample (no infection performed) (black square) and HuN fraction eluted with 1 M NaCl after on-column infection (open square-dotted line). (b) Column panning and on-column cell infection on the HuLF column with the L6 and L15 phage peptide libraries. Two panning rounds were performed. Phages from the L6 phage peptide library (solid lines): Round 1 (black square) and Round 2 (open square); phages from the L15 phage peptide library (dotted lines): Round 1 (black circle) and Round 2 (open circle ○). (c) Control of cell growth on agar plates after on-column phage infection. (left): E. coli cells which were not infected with phages were plated on agar plates containing tetracycline and incubated overnight at 37°C. (right): E. coli cells were applied to the HuLF column on which phages were bound after a panning round. After cell infection and elution, the 1 M NaCl fraction was plated on agar plates containing tetracycline and grown overnight at 37°C.