A Pilot Study: the Development of a Facility-Associated Microbiome and Its Association with the Presence of Listeria Spp. in One Small Meat Processing Facility

Microbial communities which persist in food processing facilities may have a detrimental impact on food safety and spoilage. In meat processing, Listeria monocytogenes is an organism of concern due to its ability to cause significant human illnesses and persist in refrigerated environments. The microbial ecology of Listeria spp. in small meat processing facilities has not been well characterized. Therefore, we collected samples from a newly constructed meat processing facility as an opportunity to investigate several research objectives: (i) to determine whether a stable, consistent microbiome develops in a small meat processing facility during the first 18 months of operation, (ii) to evaluate the environmental factors that drive microbial community formation, and (iii) to elucidate the relationship between microbial communities and the presence of Listeria species. We evaluated microbiomes using 16S rRNA gene sequencing and Listeria presence using quantitative PCR. We demonstrated that microbial communities differentiate by the functional room type, which is representative of several environmental differences such as temperature, sources of microbes, and activity. Temperature was an especially important factor; in rooms with low temperatures, communities were dominated by psychotrophs, especially Pseudomonas, while warmer rooms supported greater diversity. A stable core community formed in facility drains, indicating that mechanisms which cause persistence are present in the communities. The overall presence of Listeria in the facility was low but could be tied to specific organisms within a room, and the species of Listeria could be stratified by room function. IMPORTANCE This study provides critical knowledge to improve meat safety and quality from small meat processing facilities. Principally, it demonstrates the importance of facility design and room condition to the development of important microbial communities; temperature, sanitation regimen, and physical barriers all influence the ability of microorganisms to join the stable core community. It also demonstrates a relationship between the microbial community and Listeria presence in the facility, showing the importance of managing facility sanitation plans for not only pathogens, but also the general facility microbiome.