Use of an ecosystem-based approach to shed light on the heterogeneity of the contamination pattern of Listeria monocytogenes on conveyor belt surfaces in a swine slaughterhouse in the province of Quebec, Canada

The role of the accompanying microbiota in the presence of Listeria monocytogenes on meat processing surfaces is not yet understood, especially in industrial production conditions. In this study, 300 conveyor belt samples of the cutting room of a swine slaughterhouse were collected during production. The samples were subjected to the detection of L. monocytogenes and strains representative of the spatial and temporal diversities were compared with core genome multi-locus sequence typing analysis. The sequencing of the V4 region of the 16S RNA gene of the microorganisms harvested from each sample was carried out using the Illumina MiSeq platform. Diversity analyses were performed and MaAsLin analysis was used to assess the link between L. monocytogenes detection and the surrounding bacteria. The 72 isolates collected showed a low genetic diversity and important persistence characteristics. L monocytogenes isolates were not stochastically distributed on the surfaces: the isolates were detected on three out of six production lines, each associated with a specific meat cut: the half carcasses, the bostons and the picnics. The MaSLin 1 analysis identified the taxa Veillonella as a bacterial determinant of the presence of L. monocytogenes on processing surfaces. The results of this study revealed a heterogenous contamination pattern of the processing surfaces by L. monocytogenes and targeted a bacterial indicator of the presence of the pathogen. Those results could lead to a better risk assessment of the contamination of meat products.

共生菌群在肉类加工表面存在单核细胞增生李斯特氏菌（Listeria monocytogenes）过程中所发挥的作用目前仍未明确，在工业化生产环境下尤为如此。本研究于生产过程中，在某生猪屠宰场的分割车间采集了300份传送带样本。对样本开展单核细胞增生李斯特氏菌检测，并选取具有空间与时间多样性的代表性菌株开展核心基因组多位点序列分型（core genome multi-locus sequence typing）分析。采用Illumina MiSeq测序平台，对每份样本中获取的微生物的16S RNA基因V4区进行测序。开展多样性分析，并借助MaAsLin 1分析评估单核细胞增生李斯特氏菌检出情况与周边菌群之间的关联。本研究共收集到72株分离菌株，其遗传多样性较低且具备较强的定植持久性。单核细胞增生李斯特氏菌分离株并非随机分布于加工表面：该分离株在6条生产线中的3条上被检出，每条生产线分别对应特定的肉类切割品类：半胴体、猪肩肉与猪臀肉。MaAsLin 1分析鉴定出韦荣球菌属（Veillonella）可作为加工表面存在单核细胞增生李斯特氏菌的菌群指示物。本研究结果揭示了单核细胞增生李斯特氏菌对加工表面的异质性污染模式，并确定了一种可指示该病原菌存在的菌群指标。上述结果可为肉类制品污染的风险评估工作提供更精准的参考依据。