The Mechanism of Antimicrobial Peptide MPX against Enterohemorrhagic Escherichia coli in Vitro

Abstract

Escherichia coli is a facultative anaerobic bacteria that exists in the gastrointestinal tract of humans and animals. It can cause diarrhea, enteritis, destruction of the host's intestinal barrier, and intestinal microecological disturbances. In recent years, due to the abuse of traditional antibiotics, a variety of drug-resistant strains and super bacteria have emerged in an endless stream. Therefore, there is an urgent need to find new alternatives to antibiotics. Antimicrobial peptides are a type of small peptides produced when organisms resist the invasion of foreign microorganisms. They are considered to be the best alternative to antibiotics which has become a research hotspot in recent years. The antimicrobial peptide MPX is extracted from wasp venom and has a good bactericidal effect on many bacteria. To explore the effect of MPX against E. coli. The function of MPX against E. coli was detected by MIC, plate count, propidium iodide, NPN and DiSC3(5) permeability testing, immunofluorescence microscope observation, and the impact of MPX stability by temperature, pH, ion. In this study, the results found that MPX has good antibacterial activity against E. coli, and the minimum inhibitory concentration (MIC) was 31.25 ug/mL. MPX bactericidal kinetics study found that MPX had good bactericidal activity within 6 hours. Bacterial permeability studies have shown that MPX could increase the permeability of bacteria, leading to an increase in the protein content of the bacterial supernatant. In addition, NPN, PI and DiSC3(5) results showed that the fluorescence value was positively correlated with MPX. The stability test of MPX found that salt ions, temperature, pH, etc. have a slight influence on its effect. In addition, scanning electron microscopy results showed that the bacteria became smaller and the contents leaked after the action of MPX. The above results showed that MPX has a good bactericidal activity in vitro, laying the foundation for the development of new drugs for the treatment of bacterial infections.