Antibacterial Activity of Yogurt Cheese Made from Barki Sheep Milk Supplemented with Olive Oil

The purpose of this study was investigating the antibacterial effects of olive oil supplemented to cheese yoghurt made from Barki sheep milk, on the growth of some probiotic bacterial strains (Bifidobacterium bifidum (ATCC15708), Lactobacillus acidophilus (ATCC4356), Lactobacillus delbrueckii spp. bulgaricus (ATCC7995) and Streptococcus thermophilus (DSM20259) as well as some pathogenic bacterial strains. Results showed that olive oil (1%) had no effect on the growth of all probiotic bacterial strains used in Barki cheese yoghurt making. No yeasts, moulds, Enterobacteria spp and Staphylococcus spp were detected in cheese yoghurt containing olive oil (1%) through the entire storage period (21days). However, control treatment had Yeast and Moulds at the end of storage period. When four strains of pathogens were added to cheese yoghurt containing different probiotic bacteria and supplemented with olive oil (1%) then stored at 5C for 72hours, results revealed that E. coil (ACCT8739) was the most sensitive microorganism while, Staphylococcus aureus (ATCC6538) was the most resistant one. The antibacterial activity of cheese yoghurt supplemented with olive oil (1%) was higher than control treatment because olive oil supported the growth of Lactic acid bacteria. From these results, it is recommended that olive oil (1%) can be used as a natural and safe anti-microbial substance in Barki cheese yoghurt and other dairy products, and olive oil may well have the beneficial role in promoting probiotic bacteria and inhibiting harmful bacteria.