جداسازی و شناسایی باکتری های پروبیوتیکی تولید کننده اسید لاکتیک از شیر الاغ

Background : The utilization of donkey’s milk is increasing with regard to nutritional values and non-allergenic proteins. Donkey’s milk microbiota, especially lactic acid bacteria (LAB) has not yet been fully identified. This study was conducted to identify and isolate LAB with probiotic properties. Materials and Methods: Specific culture-dependent techniques and standard microbiology methods were used to identify LAB. 250 isolates were randomly picked from different donkey’s milk samples different farms in Alashtar, north of Lorestan province, Iran. Gram-staining, catalase reaction, motility test, growth at different temperatures, pH 9.6 and in presence of 6.5% NaCl as well as the ability to ferment different sugars, sodium hippurate hydrolysis and light microscope analysis were investigated. Results: Out of 250 isolates, 20 isolates were gram-positive, catalase-negative and cocci form. Enterococcus and Streptoccus genera were dominant LAB in donkey’s milk. Entreococcus faecalis (55%) and Streptococcus devriesei (45%) were among the predominant species. The results of this experiment, for the first time, reported the occurrence of Streptococcus devriesei in donkey’s milk in Iran. Conclusion: Despite high lysozyme concentration, donkey’s milk rich in probiotic LAB can be used to feed infants with allergy to cow’s milk proteins. Both Entreococcus and Streptococcus bacteria produce different types of bacteriocins which are effective against a wide range of different type of infections. Occurrence of Streptococcus devriesei in donkey,s milk may provide new research field in Iran.