Phylogenetic Profiles of In-House Microflora in Drains at a Food Production Facility: Comparison and Biocontrol Implications of Listeria-Positive and -Negative Bacterial Populations

Listeria species experience complex interactions with other microorganisms, which may promote growth and colonization of the organism in local environments or negatively affect them. This study investigated the microbial community at a food production facility, examining interactions betweenListeria and the associated microbiome.Listeria species can be transferred between zones in the production environment by individuals or equipment, and drains may act as a reservoir for the organism, reflecting the microbial flora potentially in the production environment. Drains that were colonized byListeria species and those determined to be free ofListeria were examined. In each case, 16S rRNA gene analysis was performed using the PhyloChip platform. Some general similarities in bacterial population structure were observed whenListeria -negative and -positive drain communities were compared, with some distinct differences also noted. These included increased populations of the generaPrevotella andJanthinobacterium associated with the absence ofListeria species, whereasEnterococcus andRhodococcus were in higher abundance in drains colonized byListeria species. Based on these results, a selection of bacterial species were grown in coculture biofilm with aListeria monocytogenes strain identified as having colonized a drain at the facility. Mixed-species biofilm experiments showed thatJanthinobacterium inhibited attachment and subsequent biofilm formation ofL. monocytogenes ; however,Enterococcus gallinarum significantly increased it. The results of this study suggest the microbial community in food processing facilities can impact the colonization ofListeria species and that influencing the microbiome in favor of antilisterial species may reduce the colonization ofListeria species and limit the likelihood of product/process contamination.