Department of Microbiology, University of Massachusetts, Amherst, United States; Department of Food Science, University of Massachusetts, Amherst, United States.
Department of Food Science, University of Massachusetts, Amherst, United States.
Int J Food Microbiol. 2022 Jul 16;373:109699. doi: 10.1016/j.ijfoodmicro.2022.109699. Epub 2022 May 5.
Microbial contamination of food contact surfaces in food processing industries is a significant health hazard. Evaluating the efficacy of sanitizing agents used during food processing is essential to ensure public health and safety. This study describes an optical screening method using an oCelloScope to quantify the number of surviving bacterial cells, expressed as microbial log reduction (MLR), after antimicrobial treatment. We tested the efficacy of two sanitizing agents, sodium hypochlorite and benzalkonium chloride, against desiccated cells of three pathogens, S. Enteritidis, E. coli O157: H7, and L. monocytogenes that are of concern on food processing surfaces. Stainless steel slides were used to mimic commercial food processing surfaces. Bacterial cells were desiccated at 75% relative humidity (RH) before antimicrobial treatment on stainless steel surfaces, and survivor levels were analyzed via plate counts to calculate MLR. These were compared to MLR values generated using the oCelloScope. For analysis of MLR using the oCelloScope, cells were desiccated at 75% RH on polystyrene microtiter plates, treated with antimicrobials, and surviving cell numbers were analyzed. Our results show that MLR values of treated desiccated cells calculated using the BCA algorithm of the oCelloScope were comparable to the values generated using the traditional plate count assay for the same concentration and treatment duration of the antimicrobials against all the tested pathogens. MLR could not be calculated for a non-lytic antimicrobial (curcumin and UV-A irradiation) against E. coli O157:H7, however, modified growth curves demonstrated an antimicrobial effect of curcumin and irradiation treatment. The results indicate that this method can be used for rapid screening of MLR of lytic antimicrobial compounds. Quantification of MLR using the oCelloScope is an effective tool to rapidly identify appropriate antimicrobial treatments and can be used to study novel antimicrobial compounds in the future.
食品加工行业中食品接触面的微生物污染是一个重大的健康危害。评估食品加工过程中使用的消毒剂的效果对于确保公众健康和安全至关重要。本研究描述了一种使用 oCelloScope 进行光学筛选的方法，用于量化抗菌处理后存活细菌细胞的数量，以微生物对数减少（MLR）表示。我们测试了两种消毒剂，次氯酸钠和苯扎氯铵，对三种病原体（肠炎沙门氏菌、大肠杆菌 O157：H7 和单核细胞增生李斯特菌）干燥细胞的效果，这些病原体在食品加工表面受到关注。不锈钢幻灯片用于模拟商业食品加工表面。在不锈钢表面进行抗菌处理之前，将细菌细胞在 75%相对湿度（RH）下干燥，并通过平板计数分析存活水平以计算 MLR。将这些与使用 oCelloScope 生成的 MLR 值进行比较。对于使用 oCelloScope 分析 MLR，将细胞在 75% RH 下干燥在聚苯乙烯微量滴定板上，用抗菌剂处理，并分析存活细胞数量。我们的结果表明，使用 oCelloScope 的 BCA 算法计算的处理干燥细胞的 MLR 值与使用传统平板计数法对相同浓度和处理时间的抗菌剂针对所有测试病原体生成的值相当。然而，对于一种非溶细胞的抗菌剂（姜黄素和 UV-A 照射）对大肠杆菌 O157：H7 ，无法计算 MLR，但修改后的生长曲线表明姜黄素和照射处理具有抗菌作用。结果表明，该方法可用于快速筛选溶细胞抗菌化合物的 MLR。使用 oCelloScope 定量 MLR 是一种快速识别合适抗菌处理的有效工具，可用于未来研究新型抗菌化合物。
