Li Dan, Uyttendaele Mieke
Food Microbiology and Food Preservation Research Unit, Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
Food Science and Technology Programme, Department of Chemistry, Faculty of Science, National University of Singapore, Singapore, Singapore.
Front Microbiol. 2018 Jul 30;9:1728. doi: 10.3389/fmicb.2018.01728. eCollection 2018.
Fresh produce has been identified as an important vehicle for foodborne pathogen transmission and fresh culinary herbs have occasionally been associated with human pathogens and illness. In this study, the fate of human NoV surrogates [murine norovirus 1 (MNV-1) and Tulane virus (TV)] and three strains of on pre-harvest basil () was investigated. The persistence after contamination via either leaf surface or plant substrate was tested respectively. After 3 days, both MNV-1 and TV on pre-harvest leaves were at non-detectable levels (>5.5-log reduction for MNV-1 and >3.3-log reduction for TV). The three strains showed consistent reductions of 3- to 4-log. At day 6 and 9, all the tested samples showed low levels of infectivity which were close or below the detection limits (1.7-log PFU/sample leaf for MNV-1 and TV, 0.7-log CFU/sample leaf for ) except for Thompson FMFP 899, one out of three samples showed to maintain present at exceptional high levels (day 6: 5.5-log CFU/sample leaf; day 9: 6.7-log CFU/sample leaf). Possibilities of microbial internalization into the edible parts of basil via the roots was demonstrated with both MNV-1 and Thompson FMFP 899. The infectivity of internalized MNV-1 and both decreased to non-detectable levels within 9 days after inoculation. Moreover, it should be noticed that very high microbial inoculation was used in the experimental set-up (8.46-log PFU/ml of MNV-1, 8.60-log CFU/ml of ), which is abnormal in the real-life expected contamination scenario. Within the tested scenarios in this study, contaminated on the adaxial leaf surface of basil plants while in growth, and remained/reached a high population of over 6-log CFU/sample leaf after 9 days in one out of three samples, thus showed the highest potential for causing foodborne infection.
新鲜农产品已被确定为食源性病原体传播的重要载体，新鲜药草偶尔也与人类病原体和疾病有关。在本研究中，调查了人类诺如病毒替代物[鼠诺如病毒1型（MNV-1）和图兰病毒（TV）]以及三种 菌株在收获前罗勒（ ）上的存活情况。分别测试了通过叶片表面或植物基质污染后的持久性。3天后，收获前叶片上的MNV-1和TV均处于不可检测水平（MNV-1减少>5.5个对数，TV减少>3.3个对数）。三种 菌株显示出3至4个对数的一致减少。在第6天和第9天，除了汤普森FMFP 899外，所有测试样品的感染性水平都很低，接近或低于检测限（MNV-1和TV为1.7个对数PFU/样品叶， 为0.7个对数CFU/样品叶），三个样品中的一个显示在第6天保持异常高水平（5.5个对数CFU/样品叶），在第9天保持6.7个对数CFU/样品叶。MNV-1和汤普森FMFP 899都证明了微生物通过根部内化到罗勒可食用部分的可能性。接种后9天内，内化的MNV-1和 的感染性均降至不可检测水平。此外，应该注意的是，实验设置中使用了非常高的微生物接种量（MNV-1为8.46个对数PFU/ml， 为8.60个对数CFU/ml），这在实际预期的污染情况下是不正常的。在本研究测试的场景中， 在罗勒植物生长期间污染了叶片正面，在三个样品中的一个中，9天后仍保持/达到超过6个对数CFU/样品叶的高菌量，因此显示出引起食源性感染的最高潜力。
