Study On Screening Of Lactiplantibacillus Plantarum Against Escherichia Coli And Its Antibacterial Properties

Eescherichia coli O157:H7(E.coli O157:H7)has been identified as one of the most dangerous foodborne pathogens,because it can cause hemorrhagic diarrhea,enteritis and other diseases.Currently,the use of antibiotics is the most prevalent treatment for E.coli O157:H7 infection.However,the emergence of drug-resistant and even super-resistant bacteria due to the misuse of antibiotics poses a serious threat to human health.Therefore,there is an urgent need to develop a safe,stable and effective natural antibacterial agent to reduce or even replace the use of antibiotics.According to the safe and harmless properties of Lactiplantibacillus plantarum,it has the potential to become a suitable source of natural antibacterial agents.Therefore,in this study,264 Lactiplantibacillus plantarum strains were screened for antibacterial activity against E.coli O157:H7,the properties of antibacterial substances of the obtained strains were explored,and combined the genome and proteome to mine the bacteriostatic proteins of the strains.The results of the study are as follows:1.The bacteriostatic activity of the supernatant of 264 strains of Lactiplantibacillus plantarum was determined,and 30 strains of Lactiplantibacillus plantarum which could produce proteinaceous bacteriostatic substances were obtained.The physicochemical properties of the three strains of Lactiplantibacillus plantarum with the strongest antibacterial activity were investigated,and a strain with strong antibacterial activity and good physicochemical properties was obtained.The strain-IMAU80122.2.The biological characteristics of the antibacterial substances of the strain-IMAU80122 were explored: the antibacterial activity of the strain-IMAU80122 was the highest at 18 h and with a broad-spectrum,which could damage and destroy the cell membrane permeability of E.coli and S.aureus and cause damage to cell membrane and morphological structure.3.The genome of IMAU80122 was extracted and determined,and three bacteriocin gene clusters were matched in the anti SMASH and BAGEL4 databases,which have the prerequisite for the synthesis of bacteriocin.4.The optimal saturation of ammonium sulfate precipitation was determined to be80 %;IMAU80122 was found to be very active in biosynthesis by LC-MS/MS analysis of crude protein extraction.The bipeptide bacteriocin pln EF,inducer peptide pln A and pln N were found to be consistent with the bacteriocin gene cluster sequence predicted by BAGEL4 through screening and comparison,which proved that the bacteriocin was synthesized by IMAU80122.At the same time,there were some bacteriocin-related proteins with low homology to the known sequences in the database,indicating that IMAU80122 has the potential to synthesize novel bacteriocins.In this study,a strain of Lactiplantibacillus plantarum IMAU80122 with strong antibacterial activity was screened,this strain has great potential in biosynthesizing antibacterial substances,and can become the source of bacteriocin producing strains and bioactive natural products.This idea of using the combination of genome and proteome to mine antibacterial substances is of great significance to the research on the development of microbial natural antibacterial agents.