Universidad de Guanajuato Campus Irapuato-Salamanca, División Ciencias de la Vida, Departamento de Ingeniería en Alimentos, Irapuato, Guanajuato, México, 36500.
J Food Prot. 2011 Feb;74(2):274-8. doi: 10.4315/0362-028X.JFP-10-324.
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.
在这项研究中，从墨西哥两个城市的市场和超市采集的 13%新鲜生菜（生菜）样本受到了沙门氏菌的污染。从这些样本中，扩增了约 300 个碱基对（bp）的扩增子，对应于沙门氏菌的入侵（invA）和 16S 和 23S rRNA 基因的内部转录间隔区的预期大小。此外，还分离和携带了大小约为 9 至 16 kbp 的质粒。从这些菌株中，91%对氨苄青霉素和呋喃妥因具有抗性，而 55%对头孢噻吩和氯霉素具有抗性。未检测到对阿米卡星、羧苄青霉素、头孢噻肟、庆大霉素、奈替米星、诺氟沙星和磺胺甲恶唑-甲氧苄啶的耐药性。当将沙门氏菌分离株对五种墨西哥苏云金芽孢杆菌菌株产生的新型细菌素（morricin 269、kurstacin 287、kenycin 404、entomocin 420 和 tolworthcin 524）进行测试时，有 50%对这些抗菌肽敏感。这是第一个表明从生菜中分离的沙门氏菌菌株对世界上最重要的生物杀虫剂产生的细菌素敏感的报告，这表明这些抗菌肽可作为治疗剂或食品防腐剂，以减少或破坏沙门氏菌的种群。
