Environmental Microbial & Food Safety Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland, USA.
Foodborne Pathog Dis. 2022 May;19(5):324-331. doi: 10.1089/fpd.2021.0091. Epub 2022 Mar 15.
Small fruits such as strawberries have been increasingly implicated in outbreaks of foodborne illnesses. and may contaminate strawberries leading to potential public health concern. The objective of this study was to investigate the efficacy of a combined lactic acid bacteria (LAB) treatment of and for controlling and on fresh strawberries during storage at 4°C and 10°C. Strawberries purchased from a local grocery store were separately dip inoculated with Newport, Tennessee, Thompson, or a three-strain cocktail of at ∼9 log colony-forming unit (CFU)/mL and allowed to air-dry for 1 h. Inoculated strawberries were then divided into three groups: (1) Control (pathogen alone), (2) Man, Rogosa, Sharpe (MRS) control (dipping in MRS broth), and (3) LAB treatment (dipping in a LAB cocktail of and ). After treatment, strawberries were stored at 4°C or 10°C for 7 d in vented clamshell containers. Surviving , , and LAB populations on strawberries were determined on 0, 1, 3, and 7 d post-treatment by plating on selective agars. At both 4°C and 10°C, LAB treatment significantly decreased populations by up to 2 log CFU/g compared to controls after 3 d of storage ( < 0.05). When strawberries were stored at 4°C, LAB treatment reduced ∼2.5 log, ∼2.7 log, and ∼2.9 log CFU/g in Newport, Tennessee, and Thompson populations, respectively, compared to control on day 7. Similarly, ∼2.5 log CFU/g reductions of populations were observed with LAB treatment at 10°C on day 7. LAB populations remained at ∼7.5 log CFU/g levels on strawberries at both temperatures throughout the entire study. Results of this study suggest that a combined LAB treatment can be potentially used as biocontrol agents against and on strawberries at postharvest level.
小浆果如草莓越来越多地与食源性疾病的爆发有关。 和 可能污染草莓，引起潜在的公共卫生关注。本研究的目的是研究乳酸细菌（LAB）联合处理 和 对冷藏（4°C 和 10°C）草莓中 和 的控制效果。从当地杂货店购买的草莓分别用 纽波特、田纳西州、汤普森，或三株混合菌（约 9 对数集形成单位（CFU）/mL）浸泡，风干 1 小时。然后将接种的草莓分为三组：（1）对照组（仅病原菌）、（2）Man，Rogosa，Sharpe（MRS）对照组（MRS 肉汤浸泡）和（3）LAB 处理组（LAB 鸡尾酒浸泡）。处理后，草莓在通风蛤壳容器中在 4°C 或 10°C 下储存 7 天。在处理后 0、1、3 和 7 天，通过选择性琼脂平板计数确定草莓上存活的 、 、 和 LAB 种群。在 4°C 和 10°C 下，与对照组相比，LAB 处理在储存 3 天后可使 种群减少多达 2 对数 CFU/g（<0.05）。当草莓在 4°C 下储存时，与对照组相比，LAB 处理可使 纽波特、田纳西州和 汤普森的种群分别减少约 2.5 对数、2.7 对数和 2.9 对数 CFU/g，在第 7 天。同样，LAB 处理在 10°C 下也可使 种群减少约 2.5 对数 CFU/g，在第 7 天。在整个研究过程中，LAB 种群在两种温度下的草莓上均保持在约 7.5 对数 CFU/g 水平。本研究结果表明，联合 LAB 处理可作为采后控制草莓中 和 的生物防治剂。
