Bioactive potential of polysaccharides produced by lactic acid bacteria isolated from dairy products in Egypt

Lactic acid bacteria (LAB) have attracted considerable attention because of their ability to generate exopolysaccharides (EPS).Exopolysaccharides play a crucial role in human health, demonstrating notable antitumor, antioxidant, and antimicrobial properties. This study aimed to optimize the production of EPS by lactic acid bacteria LAB isolates and evaluate their bioactivities.LAB isolates were screened for EPS production under different culture conditions. Twenty isolates with promising bioactivities were selected and further studied. The best isolate was analyzed for total sugar content and its potential as an anticancer and antiviral agent. LAB cultures showed an increase in EPS production in modified MRS medium with an initial pH of 6.8 and 37 °C. The dry polymer weight (DPW) and viscosity of EPS varied between 1500 and 17500 mg/ll, with the K1 isolate exhibiting the highest DPW. EPS exhibited notable antioxidant and antibacterial properties, with CH3, P2 and P4 showing significant bioactivity. The CH3 isolate, identified as Lactobacillus brevis, producing EPS in sweet whey medium,exhibited potential anticancer effects against Caco-2 cells and antiviral activity against HAV. The dry polymer and viscosity did not show significant differences between isolates and conditions. In summary, EPS exhibits antioxidant, antimicrobial,anticancer, and antiviral properties, suggesting potential applications in the food industry and for human health.