Phage Adsorption Modulation by Proteinase K and Periodate

To test whether proteinase K or periodate affects phage adsorption, K. pneumoniae isolates were pretreated with 20 μg/mL proteinase K (Solarbio, China), 100 mM periodate (Sigma, USA), and 50 mM sodium acetate (Sigma) for 3 h at 37°C and then coincubated with phage at room temperature for 5 min. The residual phage proportion was calculated as the percentage of phage quantities after proteinase K, periodate, or lipopolysaccharides treatment compared to the initial phage quantities. To further validate the phage inactivation caused by LPS, the LPS were extracted from host strains using an LPS extraction kit (catalog no. 17141; Intron Biotechnology, South Korea) and used in a phage inactivation test as previously described (37 (link)). Phages treated with LPS of Escherichia coli O111:B4 (Sigma) were used as a control group.