Characterization and bioactive properties of exopolysaccharides produced by Streptococcus thermophilus and Lactobacillus bulgaricus isolated from labaneh

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This study aimed to investigate and characterize the bioactivities of two novel exopolysaccharides, EPS-S and EPS-L, produced respectively by Streptococcus thermophilus and Lactobacillus bulgaricus that were newly isolated from labaneh. Both EPSs are composed of glucose and other sugars, with average molecular weights of 537.80 kDa and 248.15 kDa, ZP of −26.7 and −44.83 mV, and particle sizes of 824.5 and 757.9 nm IC50 values of EPS-S and EPS-L against colon cancer cells (HT-29, HCT-116) were 5.01 and 0.79 mg/mL and 4.20 and 3.46 mg/mL, respectively. Both EPSs displayed a bactericidal effect against Listeria monocytogenes, while EPS-L exhibited significant inhibition of methicillin-resistant Staphylococcus aureus. EPS-S inhibited 53.8% of α-amylase, 9.2% of α-glucosidase, and 25.9% of angiotensin-converting enzyme (ACE), while EPS-L inhibited 47.8% of α-amylase, 11.9% of α-glucosidase, and 52.5% of ACE. This study reveals promising biological properties of EPS-S and EPS-L for potential applications in the food and nutraceutical industries.