Evaluation of Probiotic Properties of Lactic Acid Bacteria Isolated from Dairy Products

Abstract

Seventy samples were collected from different sources, including dairy samples, soil samples, and samples of therapeutic bacteria supplements available in pharmacies to isolate and diagnose the types of lactic acid bacteria, study some of their traits that are used as bio-enhancers, and identify the most efficient isolates, De Man, Rogosa, and Sharp Agar (MRS) medium were used to isolate the bacteria of lactic acid. After the phenotypic tests for colonies and microscopic and biochemical tests were made, 38 isolates were obtained that belong to lactic acid bacteria, the results showed that most of the isolates belonged to the genus Bifidobacterium, as their number was 14 isolates with a rate of 36.8%, while the number of isolates belonging to the genus Lactobacillus was 12 with a rate of 31.57%. In addition for isolates belonging to the genus Leuconostoc, the number of isolates was 8 with a rate of 21.1%. Also, it was possible to obtain 4 isolates with a rate of 10.5% belonging to the genus Streptococcus. The biological properties of bacterial isolates that are isolated in terms of their ability to grow at different temperatures were studied, the results showed that all isolates being studied have the ability to grow at a temperature of 37° C, 42.8% of the isolates have the ability to grow at a temperature of 10° C, and 50% of the isolates have the ability to grow at a degree of 45° C, also, it appears from the results that all bacterial isolates being studied have the ability to grow in saline concentrations of 6.5%, except for two isolates; S. uberis and S. lactis, also, all bacterial isolates have the ability to grow in a saline concentration of 4.5 % except for B. bifidum, B. infants, B. breve, B. longum. The results also showed that the bacterial isolate L. lactis had the highest pH resistance, as it significantly outperformed the rest of the isolates and gave a growth rate of 123 × 103 CFU / ml, it is followed by isolate S.uberis, and then isolate B.berve, which gave an average growth rate of (113.75, 111.5) × 103 CFU/ml, in terms of its resistance to bile salts, all isolates could resist 0.2, 0.3 g/ml concentrations, L. lactis gave the highest growth rate reached 159 CFU/ml.