EXPERIMENTAL TRIALS FOR REDUCING BIOFILM-PRODUCING Escherichia coli USING Nigella sativa AND OLIVE OILS' NANOEMULSIONS

Dairy products can be contaminated from their surrounding surfaces and equipment with biofilm forming foodborne pathogens such as Escherichia coli (E. coli). Biofilm production is regarded as an adaptive mechanism that enhance microbial growth and proliferation. In sight of these facts, this study aimed to investigate of the prevalence of E. coli in dairy products (kariesh cheese, ice cream, and pasteurized milk), and dairy plant floors, and their contact equipment. Besides, the abilities of the identified E. coli serotypes to produce biofilm were further examined. In a reduction trial, the use of Nigella sativa and olive oils' nanoemulsions to reduce E. coli-biofilm formation was examined. The obtained results indicated that the prevalence rates of E. coli in the examined kariesh cheese, ice cream, pasteurized milk, dairy plant floors, and equipment were 19.05%, 4.76%, 0%, 45.24%, and 30.96%, respectively. Five E. coli serotypes were identified in the current investigation namely, E. coli O26:H11, E. coli O55:H7, E. coli O78:H-, E. coli O111:H4, and E. coli O127:H6 at variable rates. Molecular identification of the recovered E. coli serotypes revealed that all serotypes harbored E. coli-specific 16S rRNA, and fim H, biofilm-coding genes. All identified E. coli serotypes had the ability to produce biofilm in the following order: E. coli O26:H11, E. coli O55:H7, E. coli O78:H-, E. coli O111:H4, and E. coli O127:H6, respectively. Nigella sativa, and olive oils' nanoemulsions reduced biofilm production in a concentration dependent manner.