Safety evaluation and bacteriocinogenic potential of Pediococcus acidilactici strains isolated from artisanal cheeses

Abstract

Pediococcus acidilactici ST1607V, ST2104V and ST3105V, isolated from a Brazilian artisanal cheese expressed bacteriocins with high inhibitory activity against several strains of Listeria monocytogenes and Enterococcus spp., but not against most of the other tested lactic acid bacteria (LAB). Bacteriocinogenic activity against L. monocytogenes ATCC7644 was expressed with a high titre of 51200 AU/mL (ST1607V and ST2104V) and 25600 AU/mL (ST3105V), when cultured in MRS. Bacteriocins produced by strains ST1607V, ST2104V and ST3105V presented a bactericidal mode of action against L. monocytogenes ATCC7644 and Enterococcus faecium ATCC19434. DNA of the studied LAB strains was obtained and subjected to PCR assays targeting more than 50 genes related to biogenic amines production (histidine, tyrosine and ornithine decarboxylases), virulence (sex pheromones, gelatinase, cytolysin, hyaluronidase, aggregation substance, enterococcal surface protein, endocarditis antigen, adhesion of collagen, integration factors) and antibiotic resistance (vancomycin, tetracycline, erythromycin, gentamicin, chloramphenicol, bacitracin). A few safety-related genes were detected in some strains, indicating their safety for application in fermented food products. Special attention should be given to the presence of possible virulence factors, in addition to the production of biogenic amines and antibiotic resistance. Additional in vitro and in vivo experiments could be designed for future evaluation of possible expression of detected virulence genes.