الفهرس 
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Abstract
This study aimed to isolate different lactic acid bacteria from 21 sources lfdairy products i.e., ( cheese, fermented milk, goat milk), as well as Kishk lIId .pickled cucumber. The obtained bacterial isolates were then screened rough probiotic selection criteria in a step by step procedure, which eluded about 12 subsequent tests (morphological, physiological and :’ochemical tests). Afterwards, the final objective was applying some of the ielected isolates (7 isolates) presumptively probiotic lactobacilli in ’oduction of a functional dairy product. (bioyoghurt-Iike). The obtained suits could be summarized as follows:-
Isolation of lactic acid bacteria:
Based on 21 sources, a total of 122 isolates were obtained. Out of this umber, 94 bacterial isolates were found to be Gram positive, catalase egative, non spore forming and non-motile. Among the 94 bacterial lates, 48 isolates were found rod-shaped and 46 isolates were found ci-shaped, and all those isolates were retained for further assessment for tic acid bacteria possessing probiotic properties in order steps procedure, which any group of isolates showing good performance for a tested operty were again selected for the next step.
Testing of bacterial isolates for use as probiotic:
In order to confirm a strain as probiotic, the following tests i.e. acid erance,- bile tolerance, adhesion to intestinal cells, pH reduction , milk agulation, NaCI tolerance and antimicrobial activity, were subsequently nducted:
·Acid tolerance ( to pH 4): Results of the assay of 94 isolates for growth pH 4 were expressed as optical density (absobance) at 660 nm and owth increase (G.!.). For rod-shaped bacterial isolates from cheese