title: A Microplate Growth Inhibition Assay for Screening Bacteriocins against Listeria monocytogenes to Differentiate Their Mode-of-Action.
abstract: Lactic acid bacteria (LAB) have historically been used in food fermentations to preserve foods and are generally-recognized-as-safe (GRAS) by the FDA for use as food ingredients. In addition to lactic acid; some strains also produce bacteriocins that have been proposed for use as food preservatives. In this study we examined the inhibition of Listeria monocytogenes 39-2 by neutralized and non-neutralized bacteriocin preparations (Bac+ preps) produced by Lactobacillus curvatus FS47; Lb. curvatus Beef3; Pediococcus acidilactici Bac3; Lactococcus lactis FLS1; Enterococcus faecium FS56-1; and Enterococcus thailandicus FS92. Activity differences between non-neutralized and neutralized Bac+ preps in agar spot assays could not readily be attributed to acid because a bacteriocin-negative control strain was not inhibitory to Listeria in these assays. When neutralized and non-neutralized Bac+ preps were used in microplate growth inhibition assays against L. monocytogenes 39-2 we observed some differences attributed to acid inhibition. A microplate growth inhibition assay was used to compare inhibitory reactions of wild-type and bacteriocin-resistant variants of L. monocytogenes to differentiate bacteriocins with different modes-of-action (MOA) whereby curvaticins FS47 and Beef3, and pediocin Bac3 were categorized to be in MOA1; enterocins FS92 and FS56-1 in MOA2; and lacticin FLS1 in MOA3. The microplate bacteriocin MOA assay establishes a platform to evaluate the best combination of bacteriocin preparations for use in food applications as biopreservatives against L. monocytogenes.
authors.affiliation: Department of Animal Science, Oklahoma State University, Monroe Street, Stillwater, OK 74078, USA. paul.v@uky.edu.
authors.forename: Paul Priyesh
authors.initials: PP
authors.lastname: Vijayakumar
authors.affiliation: Department of Animal Science, Oklahoma State University, Monroe Street, Stillwater, OK 74078, USA. peter.muriana@okstate.edu.|Robert M. Kerr Food & Agricultural Products Centre, Oklahoma State University, 109 FAPC Building, Monroe Street, Stillwater, OK 74078-6055, USA. peter.muriana@okstate.edu.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Muriana
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000633:toxicity*; D001430:Bacteriocins / Q000737:chemistry / Q000633:toxicity*; D016983:Enterococcus / Q000737:chemistry / Q000378:metabolism; D057166:High-Throughput Screening Assays / Q000379:methods*; D007778:Lactobacillus / Q000737:chemistry / Q000378:metabolism; D008089:Listeria monocytogenes / Q000187:drug effects*; D008826:Microbial Sensitivity Tests / Q000379:methods; D010376:Pediococcus / Q000737:chemistry / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins
keywords: Listeria monocytogenes; bacteriocins; biopreservatives; inhibition; microplate assay