Evaluating the antagonistic effect of against Shiga toxigenic and non-toxigenic strains in bioyogurt.

This study was conducted to determine the effect of acidophilus yoghurt (yoghurt fortified with ) in comparison to traditional plain yoghurt ( and starter cultures) on the survival of three pathogenic strains; Shiga toxigenic O157 (STx O157), non-toxigenic O157 (Non-STx O157) and Shiga toxigenic non-O157 (STx O145). After six days of refrigerated storage of laboratory-manufactured yoghurt inoculated with the three strains of separately, all were eliminated in acidophilus yoghurt, while their survival extended in the traditional yoghurt along the storage period (17 d). Reduction percentages of the tested strains in acidophilus yoghurt were 99.93, 99.93 and 99.86%, with log reduction of 3.176, 3.176, and 2.865 cfu/g for Stx O157, Non-Stx O157, and Stx O145 respectively, in comparison to 91.67, 93.33 and 93.33%, with log reduction of 1.079, 1.176 and 1.176 cfu/g in traditional yoghurt. Statistical analysis showed a significant effect of acidophilus yoghurt in reducing the count of Stx O157 ( 0.001), Non-Stx O157 ( 0.01) and Stx O145 ( 0.01) compared to the traditional yoghurt. These findings emphasize the potential use of acidophilus yoghurt as a biocontrol alternative method for eliminating pathogenic , as well as other similar applications in the dairy industry.