Molecular Identification of potential probiotic lactic acid bacteria strains isolated from Egyptian traditional fermented dairy products

Abstract

This study aimed to isolate, identify and determine the restrictive criteria for potential probiotic Lactic Acid Bacteria (LAB) strains from artisanal soft cheese (Karish cheese) made from raw buffalo's milk and kishk, traditional Egyptian dried fermented milk wheat based mixture. One hundred strains were isolated and identified by classical phenotypic characteristics including Gram stain, shape, catalase production and biotype protocols using appropriate API system. The ability of selected LAB strains to tolerate acidic pH, resist in bile salts as a crucial criteria for potential probiotic were assessed. The antibacterial activity against food borne pathogens as a preferred capability of probiotic LAB was monitored by agar well diffusion method. Accordingly, ten isolates that were further examined for their ability to endure high osmolarity as a unique technological property needed in lactic starter preferred for processing and ripening domiati cheese, a brined ripened Egyptian soft cheese variety was screened. Results showed that two strains one as Lactobaailusspp. and the other as Enterococcus faecium spp. were promised in this regard. To confirm the species identity, two selected strains were identified by molecular biology technology based on amplified ribosomal DNA restriction analysis and 16S rDNA sequencing technique. Results indicated that the unique strains were Lactobacillus paracasei (Lb 2) and Enterococcus faecium (En 4), respectively. The impact of the study was to select probiotic lactic starter culture to be employed in processing probiotic brined soft cheese to satisfy the mounting need of local dairy industry toward production of functional dairy products.