Post-sanitation bacterial survival on meat facility environmental surfaces as delineated by biofilm formation

This work aimed was to determine post sanitation biofilm harborage at a large beef fabrication facility to better understand their potential impact on food safety by quantifying major extracellular polymeric substance components (carbohydrates, protein and eDNA), enumeration of total plate count (TPC) and Pseudomonas, and profiling of microbial communities. The sampled surfaces (n = 162) included drive and support rollers of conveyor belts, cutting saw blade covers, heads of various sprayers, dip tanks for tools (DTC), floor drains, wall corners, and floor mats. Floor mats had the highest median TPC at 6.88 log CFU/10 cm², higher than all but drains and wall corners by up to 4.0 log. Pseudomonas was highest for drains at 3.95 log CFU/10 cm². Of all sampling sites, 46.9% harbored biofilms, mostly from floor mats, DTC and wall corners. Microbiota on different surfaces and at different sampling time overlapped. The microbial community structure in biofilms and non-biofilms differed. Most genera (13/15) in non-biofilms were aerobes except for Escherichia and Clostridium. The biofilms contained 35 genera, including all of those found in non-biofilms except for Flavobacterium and additional 10 aerobic bacteria and 11 facultative/anaerobes. Notably, Pseudomonas, Acinetobacter and Escherichia, were sizable fractions of both biofilms and non-biofilms and were not associated with specific surfaces when in biofilms. A core group of 11 genera including Escherichia were found in most biofilms. Biofilms had significant fractions of facultative anaerobes, while non-biofilms had higher fractions of aerobes. The findings show persistent microbiota on post-sanitation surfaces including the food safety indicator Escherichia.