Vegetables are one of the sources from which Helicobacter pylori can be acquired. This bacterium infects >50% of the global population and is a recognized type I human carcinogen. H. pylori enters into the viable but non-culturable state when it is in the environment, and therefore the use of molecular techniques is much convenient for its detection. Free-living amoebae (FLA) are protozoans found in vegetables. They are transmission vehicles for amoeba-resistant bacteria, among which H. pylori is included. The aim of this study is to study the occurrence and viability of H. pylori from lettuce samples, H. pylori internalized into FLA and the microbiome of FLA isolated from these samples. Special focus was pointed to human pathogenic bacteria.

H. pylori was not directly detected in any lettuce sample by means of molecular techniques and neither by culture. However, intra-amoebic H. pylori DNA was detected by means of PMA-qPCR in 55% of the samples and viable intra-amoebic H. pylori cells in 25% of the samples by means of DVC-FISH technique. When FLA microbiome was studied, 21 bacterial genera were part of FLA microbiome in all samples. Helicobacter genus was detected as part of the FLA microbiome in two samples. Other bacteria of public health interest such as Aeromonas sp., Arcobacter sp., Legionella sp., Mycobacterium sp., Pseudomonas sp. and Salmonella sp. were detected as part of FLA microbiome along the analysed samples.

This study demonstrates for the first time that H. pylori is internalized as well as alive inside FLA isolated from vegetables. Moreover, this study shows that FLA promote H. pylori detection in environmental samples. In addition, as far as we are aware, this is the first study which studies the microbiome of FLA isolated from vegetables. Among the FLA microbiome, bacteria of public health interest were detected, pointing out that FLA are carriers of these pathogens which can reach humans and cause a public health concern.

蔬菜是可获取幽门螺杆菌的来源之一。该细菌感染全球人口的50％以上，是公认的I型人类致癌物。幽门螺杆菌在环境中时会进入生存状态，但无法培养，因此使用分子技术对其进行检测非常方便。自由活动的变形虫（FLA）是在蔬菜中发现的原生动物。它们是抗变形虫细菌的传播媒介，其中包括幽门螺杆菌。本研究的目的是研究的发生和存活的幽门螺杆菌从莴苣样品，幽门螺旋杆菌内化到FLA中，并从这些样品中分离出FLA的微生物组。特别关注的是人类致病细菌。

不能通过分子技术和培养方法在任何生菜样品中直接检测到幽门螺杆菌。然而，通过PMA-qPCR在55％的样品中检测到了厌氧性幽门螺杆菌DNA ，并且通过DVC-FISH技术在25％的样品中检测到了有活力的幽门内幽门螺杆菌细胞。在研究FLA微生物组时，所有样品中有21个细菌属是FLA微生物组的一部分。在两个样品中，幽门螺杆菌属作为FLA微生物组的一部分被检测到。其他具有公共卫生意义的细菌，如气单胞菌属，弓形杆菌属，军团菌属，分枝杆菌属，假单胞菌属。和沙门氏菌属。沿着被分析的样品被检测为FLA微生物组的一部分。

这项研究首次证明了幽门螺杆菌在从蔬菜中分离出来的FLA中被内在化并且还活着。此外，这项研究表明，FLA促进了环境样品中幽门螺杆菌的检测。另外，据我们所知，这是第一项研究从蔬菜中分离出的FLA微生物组的研究。在FLA微生物组中，检测到了具有公共卫生意义的细菌，并指出FLA是这些病原体的携带者，这些病原体可以传播到人类并引起公共卫生问题。