Recently, Consumers are looking for natural alternatives to chemical preservatives as their concerns about the toxicity of these chemicals and the presence of antimicrobial-resistant pathogens found in food. So, this research sought to look into the antibacterial effect of mycocins of [Debaromyces hansenii (DH) and/or Saccharomyces cerevisiae (SC)] with concentrations (200 ppm and 400 ppm) on Staph. aureus and E .coli in yoghurt samples. Results revealed decreasing of E .coli counts, Where T6 (400 ppm of Debaromyces hansenii cell-free extract + 400 ppm of Saccharomyces cerevisiae cell-free extract+ 1% E .coli strain) had the most significant results as it recorded at zero time of storage 4.9±0.02 and recorded <10 at 3rd, 6th, 9th, 12th, 15th, 18th day of storage compared with T7 (control positive) (2% yoghurt starter culture+ 1 % of E .coli strain).
Conversely, the results of Staph. aureus decreased during the storage period. Where G6 (400 ppm of Debaromyces hansenii cell-free extract + 400 ppm of Saccharomyces cerevisiae cell-free extract + 1% Staph. aureus strain) had the most significant results as it recorded at zero time of storage 4.1±0.03 and recorded at 3rd day of storage with mean value 1.3±0.01 and Staph. aureus counts were <10 at 6th, 9th, 12th, 15th and 18th day of cold storage in comparison with G7 (control positive) (2% yoghurt starter culture+ 1 % Staph. aureus strain). In conclusion, DH and SC cell-free extracts at a concentration of 400 ppm could inhibit Staphylococcus aureus and E .coli growth during the storage period.