Antimicrobial Activity And Mechanism Of PDC213,a Endogenous Peptide From Human Milk

Background Antibiotics has been widely used in modern clinical medicine,which plays huge antibacterial function.But along with the application of antibiotics,bacterial drug resistance restricts the development of antibiotics.In recent study,because of the unique molecular characteristics and antibacterial mechanism of antibacterial peptide,antibacterial peptides will become the most ideal alternative to antibiotics drugs.PDC213 is derived from breast milk,an endogenous antimicrobial peptide,which has a wide range of antibacterial activity,and which will have a good application prospects.Objective In order to study the antibacterial activity and antibacterial mechanism of PDC213 to the 6 common nosocomial pathogens in NICUs.Methods(1).PDC213 is a novel endogenous peptides found in human milk by Liquid chromatography–mass spectrometry/mass spectrometry(LC-MS/MS)technique.Bioinformatics of PDC213 indicate PDC213 is an antibacterial peptide.(2).Curve of inhibitory concentrations and disk diffusion test were used to explore the antimicrobial activity.(3).The antimicrobial activity and antibacterial mechanism of PDC213 was also evaluated using the LIVE/DEAD Bac Light Bacterial viability kit.(4).Electron microscopy experiments and DNA-binding activity were used to further indicate the antimicrobial mechanism of PDC213.Results Bioinformatics of PDC213 showed that PDC213 is a novel antibacterial peptides from human milk.PDC213 showed active antibacterial activity against S.aereus and Y.enterocolitica,the common nosocomial pathogens in neonatal intensive care units(NICUs).PDC213 could inhibit at least 80% of S.aureusand Y.enterocolitica cell growth.Zones of inhibition gel of S.aereuswas 9.93 mmin diameter and zones of inhibition gel of Y.enterocoliticawas 9.83 mm in diameter.Fluorescence microscopy showed that the number of dead bacteria in S.aureus and Y.enterocolitica was significantly higher than that in the control group.From scanning electron microscopy and transmission electron microscopy,the S.aereus and Y.enterocolitica upon treatment with PDC213 exhibited deep roughening of the bacterial surface and both seemed transparent,empty and flat,with cellular debris.DNA binding assay showed that no significant difference was found between the different concentrations of PDC213 on a 1% agarose gel after binding to a certain amount of nucleic acid DNA.Conclusion PDC213 has a strong antibacterial activity against common pathogens S.aureus and Y.enterocolitica in NICU.PDC213 kills bacteria by destroying the cell membrane of S.aureus and Y.enterocolitica,rather than killing the bacteria by binding to intracellular nucleic acids...