Biofilms in Water Hoses from the Food Processing Environment Harbor Diverse Microbial Communities

Biofilms in drinking water distribution systems are harborage sites for diverse bacteria and fungi. The presence of opportunistic pathogens in these biofilms poses a potential health threat, in food processing environments, where there is still limited knowledge on biofilms. In the current study, we investigated the presence and composition of biofilms in eight months old water hoses from a meat processing environment. First, we used optical coherence tomography (OCT) to directly visualize the biofilms on the inner wall of the water hoses. Next, we determined the bacterial and fungal load and the amount of biofilm matrix components (carbohydrates, proteins, eDNA). We further investigated the biofilm microbiota with 16S rRNA (bacteria) and ITS (fungi) sequencing. Using OCT, we detected visible biofilms in two water hoses. In contrast, by targeting the microbial load and biofilm matrix components, biofilms were observed in 14 out of 15 tested water hoses. Mycobacterium and the fungal genus Trichoderma were highly abundant in the biofilms. Bacterial genera associated with meat spoilage such as Pseudomonas, unclassified Microbacteriaceae, and Stenotrophomonas were detected at low abundances. Furthermore, fungal and bacterial genera including opportunistic pathogens (e.g. Legionella, Trichoderma) were sparsely detected. Significant differences in the beta diversities of bacterial communities between water hoses from the different sampling points were detected. In this study, the biofilms indicate that the water is a potential source for cross-contamination in the food processing environment. Future research is necessary to understand the factors and mechanisms shaping the biofilm and microbial community in water hoses in food processing environments.