Probiotic and technological characterization of selected Lactobacillus strains isolated from different egyptian cheeses

BACKGROUND: Fresh milk and natural environmental conditions are used to produce traditional cheeses. Such cheeses are produced by dozens of different types of microbes. Non-starter lactobacilli are the most responsible genus of lactic acid bacteria exhibiting key technological and health promoting traits. The purpose of this study is to isolate Lactobacillus bacteria from conventional Egyptian cheeses and analyse their probiotic potential and technological properties. RESULTS: Lactobacillus isolates (33 isolates) were isolated from different Egyptian cheeses. Our results revealed that 18.18% of the isolates were fast-acidifying, 30.3% were medium-acidifying and 51.5% were slow-acidifying isolates. The results of autolytic activity showed that 24.3% of the isolates were good autolysis, 33.3% were fair autolysis, while 42.4% were poor autolysis. Fifteen isolates produced exopolysaccharides, while 9 isolates exhibited antimicrobial activities against Lactobacillus bulgaricus 340. All the isolates were resistant to pH 3 for 3 h except isolate No. 15 (MR4). The growth rate of the isolates ranged from 42.25 to 85.25% at 0.3% bile salts after 3 h of incubation. The surviving percentage of the Lactobacillus isolates decreased with increasing incubation time or the percentage of bile salts greater than 0.3%. All the isolates grew after incubation in artificial gastric and intestinal fluids. The auto-aggregation of 15 isolates ranged from 43.13 to 72.77%. Lacticaseibacillus paracasei BD3, Lactiplantibacillus plantarum BR4 and Limosilactobacillus fermentum MR2 were sensitive to the majority of the tested antibiotics and showed good bile salt hydrolase activity. CONCLUSION: L. paracasei BD3, L. plantarum BR4 and L. fermentum MR2 were isolated from Egyptian cheeses and showed probiotic and technological characterization, which are valuable for their practical application as starters, adjunct and protective cultures in cheese making.