Purification And Activity Analysis Of Antibacterial Peptide From Musca Domestica

The larvae of housefly were induced by acupuncture, crude antimicrobial peptides Musca domestica pupae were extracted by grinding, ultrafiltration,and the method of alginate adsorption.A single active antibacterial peptide was isolated from Musca domestica pupae using Sephadex G25gel filtration, DEAE Sepharose ion-exchange chromatography and RP-HPLC according to the different nature of antimicrobial peptides. The experiment with E. coli as indicator bacteria, used the method of filter paper to detect the antibacterial activity of the antimicrobial peptide. Tricine-SDS-PAGE electrophoresis results showed that the activity of antimicrobial peptides of molecular weight of about6400kD. The peptide can be inferred a hydrophobic weak-strong anionic peptides according to the separation conditions of antimicrobial peptides.Experimental results showed that the antimicrobial peptides still had a strong antibacterial activity treated by different temperatures, different pH, as well as UV irradiation.Although the inhibition zone decreased,the antimicrobial peptide still had a strong biological activity treated by121℃. The antimicrobial peptide had no change in the basic zone of inhibition treated by pH4-12, indicating that the antimicrobial peptides in a wide pH range of antibacterial activity within the same. UV irradiation had little effect on the activity of the antimicrobial peptides. Antibacterial test results showed that the antimicrobial peptide had broad-spectrum antibacterial activity against Staphylococcus aureus and other Gram-positive bacteria, Escherichia coli and other Gram-negative bacteria and some fungi. The peptide had the strongest inhibitory activity on Staphylococcus aureus and the minimum inhibitory concentration isl92ug/mL. The mechanism of its antibacterial experiment conducted a preliminary study, this peptide not only has antimicrobial activity, as well as bactericidal effect by determination of the normal bacteria and peptide treatment bacteria growth curve. Atomic force microscopy results showed that the inhibitory mechanism of the peptide mainly broke ring of germs by inhibiting bacterial cell membrane, causing leakage of the cytoplasm of germs and led to the death.