Abstract：
Glabridin is an antimicrobial compound which can be extracted from plants, such as liquorice (Glycyrrhiza glabra) roots. Although its activity against foodborne pathogens and spoilage microorganisms has already been reported, the investigation of potential applications as a surface disinfectant is still largely unexplored. Hence, this study evaluated the disinfectant efficacy of glabridin against Listeria monocytogenes. The activity of glabridin was first tested in vitro in a nutrient-rich medium against eight strains of L. monocytogenes, including food isolates and the model strain EGDe. The tested strains showed similar susceptibility with minimal inhibitory and bactericidal concentrations of 12.5 µg/mL and 25 µg/mL, respectively. Subsequently, L. monocytogenes L6, FBR17 and EGDe were selected to assess the efficacy of glabridin against dried cells (according to the European standard EN 13697:2015 + A1:2019) and biofilm cells on stainless steel surfaces. Moreover, the impact of food residual organic matter was investigated using skim milk, cantaloupe and smoked salmon solution as soiling components. Our results showed that applying 200 µg/mL of glabridin resulted in a substantial reduction (>3 log10) of dried and biofilm cells of L. monocytogenes in standard conditions (i.e. low level of residual organic matter). Cantaloupe soiling components slightly reduced the activity of glabridin, while the efficacy of glabridin when tested with salmon and skim milk residuals was substantially affected. Comparative analysis using standardized protein contents provided evidence that the type of food matrices and type of proteins may impact the activity of glabridin as a disinfectant. Overall, this study showed low strain variability for the activity of glabridin against L. monocytogenes and shed light on the possible application of this natural antimicrobial compound as a surface disinfectant.
摘要：
Glabridin是一种抗菌化合物，可以从植物中提取，如甘草（甘草）根。尽管已经报道了其对食源性病原体和腐败微生物的活性，作为表面消毒剂的潜在应用的研究仍未得到探索。因此，本研究评估了甘草定对单核细胞增生李斯特菌的消毒效果。首先在营养丰富的培养基中对八种单核细胞增生李斯特菌进行了体外测试，包括食物分离株和模型菌株EGDe。受试菌株表现出相似的敏感性，最低抑制和杀菌浓度为12.5µg/mL和25µg/mL，分别。随后，选择单核细胞增生李斯特菌L6，FBR17和EGDe来评估甘草定对干燥细胞（根据欧洲标准EN13697：2015+A1：2019）和不锈钢表面上的生物膜细胞的功效。此外，使用脱脂牛奶调查了食品残留有机物的影响，哈密瓜和熏鲑鱼溶液作为污染成分。我们的结果表明，在标准条件下（即低水平的残留有机物），应用200μg/mL的光甘草苷导致单核细胞增生李斯特菌的干燥和生物膜细胞的大幅减少（>3log10）。哈密瓜污染成分略微降低了甘草定的活性，而当与鲑鱼和脱脂乳残留物一起测试时，glabridin的功效受到很大影响。使用标准化蛋白质含量的比较分析提供了证据，表明食物基质的类型和蛋白质的类型可能会影响甘草定作为消毒剂的活性。总的来说,这项研究表明，甘草定对单核细胞增生李斯特菌的活性具有较低的菌株变异性，并阐明了这种天然抗菌化合物作为表面消毒剂的可能应用。
