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

Abstract

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 from the cutting room of a swine slaughterhouse were collected during production. The samples were subjected to the detection of L. monocytogenes. Recovered strains were characterized by serogrouping-PCR, InlA Sanger sequencing and for their ability to form biofilm. A selection of isolates was compared with core genome multi-locus sequence typing analysis (cgMLST). The sequencing of the V4 region of the 16S RNA gene of the microorganisms harvested from each sample was carried out in parallel 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. MaAsLin biomarker analysis identified the taxa Veillonella (p ≤ 0.0397) 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. These results could lead to a better risk assessment of the contamination of meat products.

Distinct Microbiotas Are Associated with Different Production Lines in the Cutting Room of a Swine Slaughterhouse

“…It should be noted that this study is part of a larger project which was developed in two phases. The first phase aimed to evaluate spatial and temporal Listeria monocytogenes contamination on the six production lines in a swine slaughterhouse cutting room in Quebec, Canada and to identify microbial determinants of the presence or absence of the bacteria on those surfaces [ 28 ]. The current study is the second phase of that project and aims to evaluate the microbiota’s homogeneity on contact surfaces according to processing line (each line is dedicated to a specific cut of meat) and according to different visits using the samples harvested during the first phase.…”

“…The current study is the second phase of that project and aims to evaluate the microbiota’s homogeneity on contact surfaces according to processing line (each line is dedicated to a specific cut of meat) and according to different visits using the samples harvested during the first phase. The sampling procedures as well as the processing of the microbiota samples have been described in detail in the work of Shedleur-Bourguignon et al, 2021 [ 28 ].…”

“…Specifically, upon arrival at the laboratory facilities, the heads of the brushes were cut and added to Falcon tubes containing 25 mL of a solution composed of Tris-HCL (10 mM), EDTA (10 mM), and NaCl (0.85%). The used wipes were subsequently cut in half under sterile conditions at the lab and each half wipe was added to the solution and the samples were stomached (Biomérieux Canada, QC, Canada) (the other half wipe was tested in a previous study [ 28 ]). Twenty mL was then transferred into two conical tubes of 15 mL (Sarstedt Inc, Saint-Laurent, QC, Canada).…”

“…The two bacterial pellets belonging to the same sample were pooled. The total DNA of the combined bacterial pellets was then extracted and purified using a modified version of a phenol–chloroform protocol as previously described [ 28 ]. Final DNA concentration was measured using the Qubit 3.0 High Sensitivity range assay (Fisher Scientific, Ottawa, ON, Canada).…”

Co-Occurrence of L. monocytogenes with Other Bacterial Genera and Bacterial Diversity on Cleaned Conveyor Surfaces in a Swine Slaughterhouse

“…Inhibition of L. monocytogenes growth could also be the result of bacteriocin secretion by other species, such as Enterococcus faecium [ 18 ]. Other studies, in contrast, demonstrated positive interactions between L. monocytogenes and other bacterial genera [ 19 , 20 ]. Indeed, for example, Flavobacterium spp., which was part of the background microbiota of a seafood processing plant, was reported to enhance the colonization of L. monocytogenes on stainless steel surfaces [ 19 ].…”