Purification And Characterization Ofbacteriocin Produced By A Strain Ofenterococcus Faecalis TG2

Food safety and food corruption caused by microorganisms are an important challenge faced by the food industry and consumers.The abuse of chemical preservatives brings new hidden dangers in food safety.The search for effective,non-toxic natural antiseptics has become a hot spot.Bacteriocins produced by lactic acid bacteria have great potential as food preservatives.Enterococcus faecalis TG2 was isolated from fermented foods in the laboratory.Preliminary experiments showed that the strain produced antibacterial active substances.The culture supernatant was purified by saturated ammonium sulfate,cation exchange,and gel filtration chromatography.The purification yield was 16%.The inhibitory activity of the purified product was measured using Lactobacillus sakei DSMZ20017^Tas the indicator and the specific activity was 30,073.42 AU/mg,which corresponded to a 33.34-fold increase in antibacterial activity compared to unpurified culture supernatant.The purified product was identified by Tricin-SDS-PAGE appearing a single band.The purified product was 6.3362 kDa determined by LC-MS/MS.The ten amino acid of N-terminal was MTRSKKLNLR and the ten amino acid of C-terminal was ATGGAAGWKS.The results of molecular weight and amino acid sequence indicate that the substance is a bacteriocin.The activity of the bacteriocin was unaffected by pH 2-10 andlost only 50%after 121°C 30min.The antimicrobial activity of the bactriocin was not affectd by metal ions,for example Fe³⁺,Ca²⁺and so on,but was sensitive to proteolytic enzymes.Tween-20,Tween-80,Triton X-100,EDTA and 8%NaCl did not affect the bacteriocin activity and SDS was able to increas the activity of bacteriocin.Inhibitory spectrum of the bacteriocin showed a wide range of activities against Listeria,Bacillus,Pediococcus lactis.Results from PCR indicated that Ent.faecalis TG2 did not harbor any virulence genes containing ace,asa1,cylA,cylB,efaAfs and esp.Enterococcus faecalis TG2 strain has high safety performance and its bacteriocin has strong antibacterial activity,broad spectrum of inhibition,stable physical and chemical properties and might be used as bio-preservatives in food products.