Prevalence of Biofilm associated Pathogenic Escherichia coli in Seafood Pre-processing factories - A potential threat to seafood safety

Abstract

Microbial adhesion and biofilm formation on food contact surfaces in the seafood industry pose major problems and risks to human health. Escherichia coli is a common inhabitant of the intestinal tract of humans and animals and can be easily disseminated in different ecosystems through the food chain and water causing serious infection in human beings. The present study attempted to analyse the biofilm forming capacity of 90 E. coli strains isolated from food contact surfaces in seafood pre-processing plants. Quantification of biofilm formation was done by microtiter plate assay. Among them, 20% of the isolates were strong biofilm producers, 26.67% and 13.33% were moderate and weak producers respectively. Biofilm production was not observed in 40% of the isolated E. coli. All the strong biofilm producers were exo-enzyme producers, which is indicative of their capability in reducing the nutritional value of food and causing spoilage. In addition, the distribution of the genes encoding virulence and biofilm functions in strong biofilm forming E. coli isolates were examined. Multiplex PCR analysis revealed the presence of shiga toxin genes stx1 (44.44%), and stx2 (77.78%), intimin (eae, 38.89%) and enterohemolysin genes (hlyA, 66.67%). Biofilm-associated genes, sdiA and rpoS (100%), were most prevalent, while rcsA (55.56%) was least prevalent in strong biofilm producing E. coli strains. Field emission scanning electron microscopy (FESEM) showed that strain with strongest biofilm producing capability by in vitro methods established biofilm on stainless steel, plastic and rubber. The findings of this study revealed that food contact surfaces in seafood pre-processing plant harbors biofilm forming E. coli, indicating chance of contamination of seafood with E.coli and high risk of seafood-related illnesses in humans.