Probiotic potential and partial characterizations of exopolysaccharide from lactic acid bacteria isolated from camel...

Lactic acid bacteria (LAB) isolated from camel rumen and traditional dairy products were assessed for their probiotic potentials and exopolysaccharide (EPS) production. EPS were partially characterized, and their safety assessed by hemocompatibility testing in human, sheep, rabbit, and chicken red blood cells. EPS-producing isolates exhibited notable antibacterial activity against Salmonella paratyphi, but showed limited effects against Staphylococcus aureus and Enterococcus faecalis. All isolates demonstrated low resistance under acidic conditions (2.5 and 4.5) with survival rates ranging from 10 % to 60 %, while based on their bile resistance (0.3 % and 0.5 % v/w), they were classified as moderate or high resistant. The isolates showed greater resistance in the simulated intestinal environment compared to the simulated gastric environment, were non-hemolytic, arginine negative, and devoid of antibiotic resistance and other virulence genes. Three high-yield EPS producers; A-1 (Leuconostoc mesenteroides 6), A-3 (L. mesenteroides DN-1), and A-5 (Lacticaseibacillus rhamnosus SK-2), showed yields of 21.95, 18.76, and 1.14 g/L, respectively. Total sugar contents were highest in DN-1 (90.50 %), whereas total protein and phenolic contents were highest in SK-2 (1.35 % and 0.68 mg GAE/mL). The EPS (A1, A3, and A5) harbored significant antioxidant potentials with half-maximal effective concentration (EC₅₀) of 2183, 1983, and 822 μg/mL (p < 0.05), respectively. Even at the highest tested concentrations, the EPS were non-hemolytic confirming their safety. These results highlight the strain-specific EPS characteristics of the LAB isolates, their functional and safety attributes, allowing their possible applicability in functional foods, nutraceuticals, and probiotic formulations.