Combined antimicrobial effect of phage-derived endolysin and depolymerase against biofilm-forming Salmonella Typhimurium

Abstract

This study was designed to evaluate the antimicrobial activity of phage-derived endolysin (LysPB32) and depolymerase (DpolP22) against planktonic and biofilm cells of Salmonella Typhimurium (ST^KCCM). Compared to the control, the numbers of ST^KCCM were reduced by 4.3 and 5.9 log, respectively, at LysPB32 and LysPB32 + DpolP22 in the presence of polymyxin B (PMB) after 48-h incubation at 37 °C. LysPB32 + DpolP22 decreased the relative fitness (0.8) and the cross-resistance of ST^KCCM to chloramphenicol (CHL), cephalothin (CEP), ciprofloxacin (CIP), and tetracycline (TET) in the presence of PMB. The MIC_trt/MIC_con ratios of CHL, CEP, CIP, PMB, and TET were between 0.25 and 0.50 for LysPB32 + DpolP22 in the presence of PMB. These results suggest that the application of phage-encoded enzymes with antibiotics can be a promising approach for controlling biofilm formation on medical and food-processing equipment. This is noteworthy in that the application of LysPB32 + DpolP22 could increase antibiotic susceptibility and decrease cross-resistance to other antibiotics.

Keywords:

• Endolysin
• depolymerase
• biofilm
• Salmonella
• fitness
• cross-resistance

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financially supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2016R1D1A3B01008304).