1 Department of Food Science and Human Nutrition, Iowa State University , Ames, Iowa.
2 Department of Plant Sciences, North Dakota State University , Fargo, North Dakota.
Foodborne Pathog Dis. 2017 Dec;14(12):719-727. doi: 10.1089/fpd.2017.2284. Epub 2017 Sep 14.
This study focused on advancing a rapid turbidimetric bioassay to screen antimicrobials using specific cocktails of targeted foodborne bacterial pathogens. Specifically, to show the relevance of this rapid screening tool, the antimicrobial potential of generally recognized as safe calcium diacetate (DAX) and blends with cranberry (NC) and oregano (OX) natural extracts was evaluated. Furthermore, the same extracts were evaluated against beneficial lactic acid bacteria. The targeted foodborne pathogens evaluated were Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, and Staphylococcus aureus using optimized initial cocktails (∼10 colony-forming unit/mL) containing strains isolated from human food outbreaks. Of all extracts evaluated, 0.51% (w/v) DAX in ethanol was the most effective against all four pathogens. However, DAX when reduced to 0.26% and with added blends from ethanol extractions consisting of DAX:OX (3:1), slightly outperformed or was equal to same levels of DAX alone. Subculture of wells in which no growth occurred after 1 week indicated that all water and ethanol extracts were bacteriostatic against the pathogens tested. All the targeted antimicrobials had no effect on the probiotic organism Lactobacillus plantarum. The use of such rapid screening methods combined with the use of multistrain cocktails of targeted foodborne pathogens from outbreaks will allow rapid large-scale screening of antimicrobials and enable further detailed studies in targeted model food systems.
本研究旨在开发一种快速比浊生物测定法，使用特定的靶向食源性致病菌混合物筛选抗菌剂。具体来说，为了展示这种快速筛选工具的相关性，评估了公认安全的钙乙二胺（DAX）及其与蔓越莓（NC）和牛至（OX）天然提取物混合物的抗菌潜力。此外，还评估了相同提取物对有益的乳酸杆菌的作用。使用从人类食品暴发中分离的菌株优化初始混合物（约 10 个菌落形成单位/mL）评估了评估的靶向食源性病原体大肠杆菌 O157:H7、沙门氏菌、单核细胞增生李斯特菌和金黄色葡萄球菌。在所评估的所有提取物中，乙醇中 0.51%（w/v）的 DAX 对所有四种病原体最有效。然而，当 DAX 降低至 0.26%并添加乙醇提取物中的 DAX:OX（3:1）混合物时，其效果略优于或等同于单独使用相同水平的 DAX。在 1 周后未生长的孔的亚培养表明，所有水和乙醇提取物对测试的病原体均具有抑菌作用。所有靶向抗菌剂对益生菌植物乳杆菌均没有影响。这种快速筛选方法的使用与从暴发中使用靶向食源性病原体的多菌株混合物相结合，将允许对抗菌剂进行快速的大规模筛选，并能够在靶向模型食品系统中进行进一步的详细研究。
