Production and Biological Activities of Exopolysaccharides Synthesized by Thermophilic Bacilli Isolated from Hot Springs in Türkiye

A total of one hundred seven thermophilic bacteria were screened for their ability to produce exopolysaccharides. Nine isolates belonging to Geobacillus , Parageobacillus , Aeribacillus and Anoxybacillus genera with highest EPS quantities were chosen and purified EPSs used for biological activity studies. EPS yields of selected thermophilic bacteria ranged between 117–419 mg/L. Among the tested EPSs, 61, 106 and 261 showed antibacterial effect against E. faecalis JH2-2 at a concentration of 15 mg/mL. EPS samples had significant antioxidant capacity, especially EPS 134, with highest DPPH radical scavenging activity of 100% at a concentration of 5 mg/mL and strongest reducing power. EPS 20, showed highest lipid peroxidation inhibition effect at a rate of 31%. EPSs displayed weak alpha amylase inhibition activity when compared with standart acarbose. The prebiotic indices of EPSs 20, 61, 76, 89, 134 and 261 were found to be higher than that of inulin, a representative prebiotic carbohydrate for all tested lactic acid bacteria in the study. All examined EPSs inhibited the biofilms formed by various bacteria depending on the test strain. Results indicated that thermophilic EPSs had remarkable antioxidant, prebiotic, and antibiofilm activities. Therefore, EPSs characterized in this study may have technological applications in health and food fields.