Abstract Listeria monocytogenes is a potentially deadly psychrotrophic pathogen that can cause illness through contamination of ready-to-eat (RTE) foods. In this work we evaluated the use of a fermentate consisting of cells and supernatant of a nisin producing Lactococcus lactis strain to control L. monocytogenes in foods. In addition, to determine the role of nisin production in this activity, a transposon screen was carried out to isolate a nisin-negative mutant. Several independent mutants containing transposon insertions in the nisin gene cluster were obtained which exhibited a complete loss of anti-L. monocytogenes activity in an agar-based assay. A simple media using food grade components was found to support strong growth and nisin production of Lc. lactis 537 following incubation at between 20 and 35 °C. The ability of the fermentate to control L. monocytogenes in foods was evaluated in cut iceberg lettuce and RTE sliced ham stored at 4 °C for 10 days. Initial levels of 103–104 CFU/g L. monocytogenes were reduced to below detection limit (

中文翻译：

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使用含有乳酸乳球菌发酵物的乳酸链球菌素控制即食火腿和鲜切卷心莴苣上的单核细胞增生李斯特菌

摘要 单核细胞增生李斯特菌是一种潜在致命的嗜冷病原体，可通过污染即食 (RTE) 食品而导致疾病。在这项工作中，我们评估了使用由细胞和乳酸链球菌产生的乳酸乳球菌菌株的上清液组成的发酵物来控制食品中的单核细胞增生李斯特氏菌。此外，为了确定乳链菌肽生产在该活动中的作用，进行了转座子筛选以分离乳链菌肽阴性突变体。获得了在乳链菌肽基因簇中含有转座子插入的几个独立突变体，它们表现出抗-L 的完全丧失。基于琼脂的测定中的单核细胞增生症活性。发现使用食品级成分的简单培养基支持 Lc 的强劲生长和乳链菌肽生产。在 20 到 35 °C 下孵育后，lactis 537。在 4 °C 下储存 10 天的切开的卷心莴苣和 RTE 切片火腿中评估发酵物控制食物中单核细胞增生李斯特氏菌的能力。103–104 CFU/g 单核细胞增生李斯特氏菌的初始水平降低到检测限以下（