摘要
Listeria monocytogenes is the etiological agent of listeriosis,a severe disease with mortality rates of up to 30%,particularly in immunocompromised individuals.Its ability to form biofilms in food processing environments hinders removal by conventional sanitizers,increasing the risk of contamination in ready-to-eat foods.This study aimed to synthesize silver nanoparticles(AgNPs)using cell-free supernatant(CFS)from Pediococcus acidilactici CE51 and evaluate their effectiveness against L.monocytogenes biofilms.Bac-AgNPs were characterized by dynamic light scattering,polydispersity index(PDI),zeta potential,UV-Vis spectrophotometry,and scanning electron microscopy.Bac-AgNPs(164 mg/mL)showed an average size of 131.8±2.7 nm,PDI of 0.28±0.02,zeta potential of-19.7±0.6 mV,and a maximum absorbance peak at 420 nm.SEM revealed predominantly spherical nanoparticles.Toxicity assays in Galleria mellonella showed 100%survival,while exposure to AgNO_(3) reduced larval survival by 40%after 96 h.Against L.monocytogenes,Bac-AgNPs demonstrated a MIC of 82 mg/mL,MBC of 164 mg/mL,and promoted a 3.06 log CFU/mL reduction.Antimicrobial activity was preserved at pH 2 and 7,but declined at pH 9 and after 7 days of storage at 4℃.In biofilm assays,Bac-AgNPs alone reduced bacterial counts by 2.5 log CFU/mL after 24 h,while the combination with CFS yielded reductions of up to 1.58 log CFU/mL at 1 h and 2.5 log CFU/mL at 24 h.These findings demonstrate that Bac-AgNPs synthesized using P.acidilactici CE51 possess promising antimicrobial and antibiofilm properties,good biocompatibility,and potential application in food safety,despite stability limitations.
