The lactic acid bacteria with broad-spectrum antimicrobial effect of Class Ⅱ bacteriocin quorum sensing system were screened and identified.After exclusion of hydrogen peroxide and organic acid interference and treatment with trypsin,pepsin and proteinase K,lactic acid bacteria secreting bacteriocin with broad-spectrum antibacterial effect was screened by Oxford cup method.The minimal inhibitory concentration was detected by assay on minimal inhibitory activity.Phylogenetic tree was constructed based on 16S rDNA homology analysis.The primers specific for five operon plnEFI,plnJKLR,plnGHSTUV,plnABCD,and plnMNOP of the class Ⅱ bacteriocins were designed.Class Ⅱ bacteriocin genes of quorum sensing system were identified by PCR and electrophoresis.The molecular size of bacteriocin was determined by UPLC and urea-sds-page.L-4 was a kind of gram positive bacteria with broad spectrum antimicrobial activity.The diameters of inhibition zones for indicator bacteria were (18.83 ± 0.39) mm and (19.96 -±0.49) mm,with the minimal inhibitory concentrations of 55.68 μg/mL and 57.31 μg/mL.L-4 had Class Ⅱ bacteriocin gene of quorum sensing system.It could secrete a bacteriocin with molecular weight of 10 ku in the molecular range of Class Ⅱ bacteriocin.L-4 was a strain of Lactobacillus plantarum secreting 10 ku of Class Ⅱ bacteriocin with broad-spectrum antimicrobial activity.