Abstract The main aim of this study was to localise, identify and characterise the Listeria monocytogenes-harbouring bacterial communities present in food related premises via 16S rRNA gene metagenetic analysis. With this scope, 319 environmental samples coming from a wide variety of surfaces of fish (n = 120), meat (n = 80) and dairy industries (n = 119), were firstly analysed following ISO 11290–1 and ISO 11290–2 norms. Direct L. monocytogenes quantification was possible in 9 samples (2.8%) with values between 2.00 and 3.97 log CFU/cm2. After enrichment, an overall L. monocytogenes incidence of 12.54% (n = 40) was obtained, being samples from meat industry the most contaminated. Molecular serotyping assays showed that most of the isolates belonged to 1/2b-3b-7 subgroup, followed by 1/2a-3a and 1/2c-3c. These results combined with AscI and ApaI PFGE macrorestriction patterns, yielded 7 different L. monocytogenes clusters. Nevertheless, no clear ecological relationships could be stablished. High amounts of L. monocytogenes-associated psychrotrophic microbiota were obtained in all cases with values above 9 log CFU/cm2 in some cases. Metagenetic analysis of one representative sample per each food industry type (fish, meat, dairy) demonstrated that Actinobacteria (53.16%) was mostly present in the meat sample whereas Proteobacteria was the most representative phylum in dairy (69.58%) and fish (97.11%) samples. Subsequent operational taxonomic units (OTUs) analysis, showed a wide variety of taxa associated with L. monocytogenes such as spoilage-associated genera (e.g. Psyschromonas or Shewanella), lactic acid bacteria genera (e.g. Lactococcus or Lactobacillus) or pathogenic species such as Yersinia enterocolitica. It was thus demonstrated, that L. monocytogenes is capable to both survive with different bacteria in different ecological niches, highlighting once more the need for proper surveillance schedules so as to guarantee the safety of the food products.

中文翻译：

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食品相关工业环境中存在的单核细胞增生李斯特菌群落的鉴定和宏遗传学特征

摘要 本研究的主要目的是通过 16S rRNA 基因宏遗传分析定位、鉴定和表征食品相关场所中存在的携带单核细胞增生李斯特菌的细菌群落。在此范围内，首先按照 ISO 11290–1 和 ISO 11290–2 分析了来自鱼类 (n = 120)、肉类 (n = 80) 和乳制品行业 (n = 119) 的各种表面的 319 个环境样本规范。在 2.00 和 3.97 log CFU/cm2 之间的 9 个样品 (2.8%) 中可以直接定量单核细胞增生李斯特菌。富集后，获得了 12.54% (n = 40) 的单核细胞增生李斯特氏菌的总体发生率，是受污染最严重的肉类工业样本。分子血清分型分析表明，大多数分离株属于 1/2b-3b-7 亚群，其次是 1/2a-3a 和 1/2c-3c。这些结果与 AscI 和 ApaI PFGE 宏观限制模式相结合，产生了 7 个不同的单核细胞增生李斯特氏菌簇。然而，没有建立明确的生态关系。在所有情况下都获得了大量与单核细胞增生李斯特菌相关的嗜冷微生物群，在某些情况下其值高于 9 log CFU/cm2。每个食品行业类型（鱼、肉、乳制品）的一个代表性样本的宏遗传分析表明，放线菌 (53.16%) 主要存在于肉类样本中，而变形菌门是乳制品 (69.58%) 和鱼类 (97.11%) 中最具代表性的门) 样品。随后的操作分类单元 (OTU) 分析显示了与单核细胞增生李斯特菌相关的多种分类群，例如腐败相关属（例如 Psyschromonas 或 Shewanella）、乳酸菌属（例如 乳球菌或乳杆菌）或致病菌种，例如小肠结肠炎耶尔森氏菌。因此证明，单核细胞增生李斯特菌能够在不同的生态位中与不同的细菌一起生存，再次强调需要适当的监测时间表，以保证食品的安全。