الفهرس 
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Abstract
Customers’ demand for natural dairy products along with the growing concerns about the antimicrobial resistance emphasized the significance of continued research into natural alternatives. Therefore, the first part of this study surveyed the microbial quality of 60 samples of white soft cheese and baladi yoghurt (30 of each), sold in the Egyptian markets with assessing the prevalence of Staphylococcus aureus, Echerichia coli and Pseudomonas aeruginosa. Additionally, phenotypic and genotypic assessments of their antimicrobial resistance patterns were evaluated, along with the molecular identification of the slt1, slt2, and eaeA virulence genes in the isolated E. coli. The samples under examination had high level of contamination with aerobic mesophilic microorganisms, yeast, mold, staphylococci, coliforms and Pseudomonas species. Biochemical and molecular identification confirmed the presence of S.aureus, E.coli, and P.aeruginosa in the examined samples. All S. aureus isolates (n=34) were phenotypically resistant to methicillin, and 77% (7/9) of them carried the MecA gene. Slt1 and slt2 genes were present in all E. coli isolates (n=3), while eaeA gene was present in two of them (66%). Moreover, all isolated strains of P. aeruginosa were resistant to all of the tested antibiotics (n=10) except for meropenem. The second part evaluated the antimicrobial activity of lactoferrin (LF) and Essential oils (clove and ginger) Nano emulsions against some pathogenic microorganisms with viability studies in fermented dairy products. LF exhibited significant antimicrobial activity, particularly against E. coli and S. typhimurium with MIC value of 0.001 and 0.01mg/ml, respectively. It reduced the survivability of Shiga toxin producing E.coli (STEC) by 91% in the lab-manufactured yoghurt by the third day of cold storage and enhanced its sensory properties without interfering with the activity of the starter culture. Essential oils (EOs) Nano emulsions demonstrated a good antimicrobial effect against the tested microorganisms. Clove and ginger Nano emulsion completely reduced S.aureus by the end of the second and third week, respectively, without affecting the sensory properties of the fortified labneh (P > 0.05).
In conclusion, this study opens a new interesting prospective for the use of LF and Nano emulsion EOs application as potent natural preservatives alternatives in the dairy products.