Phenotypic and Genotypic Detection of Zoonotic Foodborne Pathogens from Dairy Environment and Raw Milk with Special Reference to Biofilm Production

Milk and milk products can harbour multiple varieties of foodborne pathogens, such as Staphylococcus aureus, Shigella like toxin producing E. coli, Salmonella and Bacillus cereus.Many food-borne outbreaks have been associated with dairy products as main vehicles for transmission.In this study, a total of (n=310) samples were collected from different places dairies, gaushalsa, local shops and vendors of Mathura region.Swabs were taken from milking buckets (50), dippers (64), canes (56) and raw milk (140) from cows.Samples were screened for S. aureus and Shiga toxin producing E. coli (STEC) by streaking on selective agar and molecularly characterized for housekeeping nuc and stx gene by m-PCR.Overall prevalence of S. aureus and STEC was revealed 80.64% and 7.41%, respectively.Confirmed S. aureus and STEC isolates were screened for biofilm formation capability by phenotypic method methods viz Congo red agar (CRA) assay, Tube Method (TM) and Tissue Culture Plate method (TCP).On CRA 9.2 % isolates of S. aureus were positive and 90.8% were negative while TM revealed 79.2%, 12.4% and 8.4% strong, moderate and weak biofilm formers.In TCP method, 91.6% isolates were strong, 5.6% moderate and 2.8% weak biofilm producers.Among STEC isolates, 34.78 % and65.22%were positive and negative on CRA while by TM, 43.47%, 26.08% and 30.43% were strong, moderate and weak biofilm formers.In another TCP assay, 52.17%, 30.43% and 17.39 % isolates were strong, moderate and weak biofilm producers, respectively.Among these three methods TCP was found more sensitive for S aureus as well as STEC.Under Scanning electron microscopy, the 3D structure of biofilms of S. aureus and STEC revealed and the biofilms were well organized, with intact cell-to-cell connections.STEC produced better biofilm than S aureus.This study revealed that biofilm forming S. aureus and STEC were obtained from dairy utensils and raw milk so, may be a sustainable source of contamination of dairy products.So, there is need of paying more attention to the cleaning and sanitizing processes of food contact surfaces to ensure the public health.