Sun Yeting, Wang Dan, Ma Yue, Guan Hongyang, Liang Hao, Zhao Xiaoyan
College of Food Science, Shenyang Agricultural University, Shenyang 110866, China.
Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing Key Laboratory of Agricultural Products of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and rural affairs, Beijing 100097, China.
Microorganisms. 2019 Oct 28;7(11):499. doi: 10.3390/microorganisms7110499.
Contamination of fresh cucumbers ( L.) with O157:H7 can impact the health of consumers. Despite this, the pertinent mechanisms underlying O157:H7 colonization and internalization remain poorly documented. Herein we aimed to elucidate these mechanisms in cucumbers using an inverted fluorescence microscope and hyperspectral microscopy. We observed that O157:H7 primarily colonized around the stomata on cucumber epidermis without invading the internal tissues of intact cucumbers. Once the bacterial cells had infiltrated into the internal tissues, they colonized the cucumber placenta and vascular bundles (xylem vessels, in particular), and also migrated along the xylem vessels. Moreover, the movement rate of O157:H7 from the stalk to the flower bud was faster than that from the flower bud to the stalk. We then used hyperspectral microscope imaging to categorize the infiltrated and uninfiltrated areas with high accuracy using the spectral angle mapper (SAM) classification method, which confirmed the results obtained upon using the inverted fluorescence microscope. We believe that our results are pivotal for developing science-based food safety practices, interventions for controlling O157:H7 internalization, and new methods for detecting O157:H7-plant interactions.
新鲜黄瓜（L.）被O157:H7污染会影响消费者健康。尽管如此，O157:H7定殖和内化的相关机制仍鲜有文献记载。在此，我们旨在利用倒置荧光显微镜和高光谱显微镜阐明黄瓜中的这些机制。我们观察到，O157:H7主要定殖在黄瓜表皮的气孔周围，而不会侵入完整黄瓜的内部组织。一旦细菌细胞渗入内部组织，它们就会定殖在黄瓜胎座和维管束（特别是木质部导管）中，并且还会沿着木质部导管迁移。此外，O157:H7从茎到花芽的移动速度比从花芽到茎的移动速度快。然后，我们使用高光谱显微镜成像，通过光谱角映射器（SAM）分类方法对浸润和未浸润区域进行了高精度分类，这证实了使用倒置荧光显微镜获得的结果。我们认为，我们的结果对于制定基于科学的食品安全措施、控制O157:H7内化的干预措施以及检测O157:H7与植物相互作用的新方法至关重要。
