title: Isolation of Salmonella spp. from lettuce and evaluation of its susceptibility to novel bacteriocins of Bacillus thuringiensis and antibiotics.
abstract: In this study, 13% of fresh lettuce (Lactuca sativa) samples collected from markets and supermarkets in two cities of Mexico were contaminated with Salmonella spp. From those samples, amplicons of ∼300 base pairs (bp) were amplified, corresponding to the expected size of the invasion (invA) and internal transcribed spacer regions of the 16S and 23S rRNA genes of Salmonella spp. Additionally, Salmonella strains were isolated and harbored plasmids ranging from ∼9 to 16 kbp. From these strains, 91% were resistant to ampicillin and nitrofurantoin, whereas 55% were resistant to cephalothin and chloramphenicol. No resistance was detected to amikacin, carbenicillin, cefotaxime, gentamicin, netilmicin, norfloxacin, and sulfamethoxazole-trimethoprim. When Salmonella isolates were tested against novel bacteriocins (morricin 269, kurstacin 287, kenyacin 404, entomocin 420, and tolworthcin 524) produced by five Mexican strains of Bacillus thuringiensis, 50% were susceptible to these antimicrobial peptides. This is the first report showing that Salmonella strains isolated from lettuce are susceptible to bacteriocins produced by the most important bioinsecticide worldwide, suggesting the potential use of these antibacterial peptides as therapeutic agents or food preservatives to reduce or destroy populations of Salmonella spp.
authors.affiliation: Universidad de Guanajuato Campus Irapuato-Salamanca, División Ciencias de la Vida, Departamento de Ingeniería en Alimentos, Irapuato, Guanajuato, México, 36500.
authors.forename: Cristobal
authors.initials: C
authors.lastname: Castañeda-Ramírez
authors.forename: Viridiana
authors.initials: V
authors.lastname: Cortes-Rodríguez
authors.forename: Norma
authors.initials: N
authors.lastname: de la Fuente-Salcido
authors.forename: Dennis K
authors.initials: DK
authors.lastname: Bideshi
authors.forename: M Cristina
authors.initials: MC
authors.lastname: del Rincón-Castro
authors.forename: J Eleazar
authors.initials: JE
authors.lastname: Barboza-Corona
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001413:Bacillus thuringiensis / Q000378:metabolism; D001430:Bacteriocins / Q000096:biosynthesis / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005516:Food Microbiology; D005520:Food Preservatives / Q000494:pharmacology; D006801:Humans; D018545:Lactuca / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D012329:RNA, Bacterial / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012338:RNA, Ribosomal, 23S / Q000032:analysis; D012475:Salmonella / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D005520:Food Preservatives; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S