Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, MS 39762, USA.
Int J Food Microbiol. 2012 Apr 2;155(1-2):82-8. doi: 10.1016/j.ijfoodmicro.2012.01.010. Epub 2012 Jan 21.
Single and combined effects of three GRAS (generally recognized as safe) antimicrobials including, bacteriophage P100 (phage P100), lauric arginate (LAE), and potassium lactate-sodium diacetate mixture (PL-SD) were evaluated against Listeria monocytogenes cold growth in queso fresco cheese (QFC). The fate of phage P100 when exposed to LAE (200 ppm) or PL-SD (2.8% PL and 0.2% SD) was determined at 4°C and 30°C in a broth model. Phage P100 was found to be stable in the presence of these antimicrobial agents as plaque forming units (PFU) did not vary between control, LAE or PL-SD treatments. When 9 log CFU/ml of stationary phase cells of L. monocytogenes was exposed to these antimicrobials in tryptic soy broth, there was a 3 to 5 log CFU/ml reduction with phage P100 and a complete 9 log CFU/ml reduction with LAE but no measurable reduction with PL-SD after 24h at 4°C or 30°C. In QFC, the L. monocytogenes populations increased from the initial 3.5 log CFU/cm(2) to 7.7 log CFU/cm(2) in 28 days at 4°C. Treatment with 7.8 log PFU/cm(2) of phage P100 or 200 ppm of LAE showed strong listericidal effect initially by reducing L. monocytogenes counts by 2 to 3.5-4 log CFU/cm(2) while there was a subsequent regrowth of L. monocytogenes at 4°C. Treatment with PL-SD showed strong listeriostatic effect without decreasing L. monocytogenes counts but growth was prevented for 28 days at 4°C. Only the combined treatment of listericidal phage P100 or LAE with listeriostatic PL-SD reduced the initial L. monocytogenes counts by 2-4 log CFU/cm(2) and also kept the L. monocytogenes counts at that reduced level in QFC for 28 days at 4°C.
单一和三种 GRAS（一般认为安全）抗菌剂的组合效应，包括噬菌体 P100（噬菌体 P100）、月桂酰精氨酸（LAE）和乳酸钾-双乙酸盐混合物（PL-SD），被评估用于防止鲜奶酪（QFC）中李斯特菌的冷生长。在肉汤模型中，在 4°C 和 30°C 下，确定了噬菌体 P100 在暴露于 LAE（200ppm）或 PL-SD（2.8%PL 和 0.2%SD）时的命运。噬菌体 P100 在这些抗菌剂存在下是稳定的，因为在对照、LAE 或 PL-SD 处理之间，噬菌斑形成单位（PFU）没有变化。当 9 log CFU/ml 的李斯特菌静止期细胞暴露于这些抗菌剂在胰蛋白酶大豆肉汤中，噬菌体 P100 减少了 3 到 5 log CFU/ml，LAE 完全减少了 9 log CFU/ml，但在 4°C 或 30°C 下 24 小时后，PL-SD 没有可测量的减少。在 QFC 中，李斯特菌种群从初始的 3.5 log CFU/cm(2)在 4°C 下 28 天内增加到 7.7 log CFU/cm(2)。用 7.8 log PFU/cm(2)的噬菌体 P100 或 200ppm 的 LAE 处理，通过将李斯特菌的数量减少 2 到 3.5-4 log CFU/cm(2)，最初表现出强烈的杀菌作用，而在 4°C 下，李斯特菌随后出现了再生长。PL-SD 处理表现出强烈的抑菌作用，而不降低李斯特菌的数量，但在 4°C 下 28 天内阻止了生长。只有杀菌噬菌体 P100 或 LAE 与抑菌 PL-SD 的联合处理才能将初始李斯特菌数量减少 2-4 log CFU/cm(2)，并在 4°C 下将李斯特菌数量保持在 QFC 中的降低水平 28 天。
