Characterization of the bacterial community in a floor drain located in the slaughtering department of a commercial meat processing plant

Floor drains (FD) are commonly found in food processing environments to facilitate the drainage of liquids and to prevent the accumulation of water on the production floor. However, if not properly maintained and cleaned, FD can serve as a micro environment conducive to the proliferation of various microorganisms. This microbial presence raises concerns about potential food contamination posing a threat to the safety, quality and shelf life of the final product. The objective of this study was to characterize the bacterial community and its dynamic changes in a FD located in the slaughtering department of a commercial meat processing plant over one-year processing period. Across four slaughtering sets (Set 1, Set 2, Set 3, Set 4), the FD inner surface (IS), as well as the back of the covering grid (CG), were swabbed using sterile sponges on two occasions with a one-week interval. Samples were analyzed for total aerobic mesophilic and Enterobacteriaceae counts. After DNA extraction, sequencing of the 16S rRNA gene amplicons (V3-V4 region, long oligo-PCR approach) was used to characterize the bacterial population of the FD. Enumeration did not vary significantly between samples taken within one-week interval. some significant differences were observed between slaughtering sets (p = 0.04), with logarithmic variation below 1.55 log CFU/cm2. Alpha diversity (Shannon, p = 0.04) and beta-diversity (Wunifarac, p = 0.05) revealed a certain degree of variation of IS bacterial population between samples taken at the initial and subsequent time points within the one-week interval. Genera relative abundance revealed dynamic fluctuations in IS bacterial composition over the one-year period. The bacterial population of the CG showed more stability over the same period. Overall, the results suggest that the CG and IS presented different microbial ecosystems. The bacterial community within the same FD varied to a certain degree with the location in its structure and that many factors, yet to be studied, influenced its composition.