Department of Food Science, Center for Food Safety, University of Arkansas System Division of Agriculture, Fayetteville, AR 72704, USA.
Department of Food Science, Center for Food Safety, University of Arkansas System Division of Agriculture, Fayetteville, AR 72704, USA.
J Food Prot. 2023 Oct;86(10):100154. doi: 10.1016/j.jfp.2023.100154. Epub 2023 Aug 26.
This study aimed to determine the persistence of Salmonella Javiana, Listeria monocytogenes, and Listeria innocua in nonsterile, hydroponic nutrient solution (NS) at 15, 25, 30, and 37°C over a 21-day period to mimic time from seedling to mature lettuce. Bacteria were inoculated in modified Hoagland's NS at 10 CFU/mL and maintained at 15, 25, 30, and 37°C. Samples were collected at various time points, and bacteria were quantified. A mixed model was used to determine the effect of bacteria type, time (day), and temperature on bacteria concentration (log CFU/mL). The least-squares means were calculated to compare the mean log CFU/mL, and the mean values were compared with Tukey-Kramer honest significant difference test with a significance level of P = 0.05. Statistical analysis indicated that a 3-way interaction effect between temperature, time, and bacteria type had a significant impact on bacterial persistence in NS (P < 0.0001). At all temperatures, S. Javiana persisted in NS throughout the 21-day study period, compared to L. innocua and L. monocytogenes where persistence was limited to between 1 and 14 days. Similarly, decimal reduction values (D-values) of S. Javiana indicated longer persistence in NS than L. innocua and L. monocytogenes at most temperatures. For instance, at 15°C and 25°C, D-values for S. Javiana were estimated at 82 and 26 d, respectively, compared to D-values of 3.6 and ∼3 d for L. monocytogenes. Data indicate that the temperature of NS has a differential effect on the persistence of S. Javiana and Listeria spp. This study furthers the understanding of potential food safety risks associated with hydroponic systems and will contribute to the refinement of further studies to aid in the development of operation-specific risk profiles.
本研究旨在确定沙门氏菌（Salmonella Javiana）、单增李斯特菌（Listeria monocytogenes）和无害李斯特菌（Listeria innocua）在非无菌水培营养液（NS）中的持久性，营养液在 15、25、30 和 37°C 下持续 21 天，以模拟从幼苗到成熟生菜的时间。将细菌以 10 CFU/mL 的浓度接种于改良霍格兰氏 NS 中，并保持在 15、25、30 和 37°C。在不同时间点采集样品并定量细菌。使用混合模型确定细菌类型、时间（天）和温度对细菌浓度（log CFU/mL）的影响。计算最小二乘均值以比较平均 log CFU/mL，并用 Tukey-Kramer 诚实显著差异检验（显著水平 P=0.05）比较平均值。统计分析表明，温度、时间和细菌类型之间的 3 重交互效应对 NS 中细菌的持久性有显著影响（P<0.0001）。在所有温度下，沙门氏菌在整个 21 天的研究期间都能在 NS 中持续存在，而无害李斯特菌和单增李斯特菌的持久性仅限于 1 至 14 天。同样，沙门氏菌的十进制减少值（D 值）表明，在大多数温度下，沙门氏菌在 NS 中的持久性长于无害李斯特菌和单增李斯特菌。例如，在 15°C 和 25°C 下，沙门氏菌的 D 值估计分别为 82 和 26d，而单增李斯特菌的 D 值分别为 3.6 和~3d。数据表明，NS 的温度对沙门氏菌和李斯特菌属的持久性有不同的影响。本研究进一步了解了与水培系统相关的潜在食品安全风险，并将有助于进一步研究的细化，以帮助制定特定操作的风险概况。
