TAGRA 2025

Exopolysaccharides (EPS) are macromolecules with structural diversity that play important roles in various biological processes. EPSs obtained from natural sources such as plants, algae, fungi, and bacteria exhibit a broad pharmacological spectrum, including antitumor, immunomodulatory, and antioxidant effects. Microbial polysaccharides offer significant advantages over plant or animal polysaccharides due to their sustainable production, rapid proliferation, controllable fermentation conditions, and high purity. In recent years, three-phase separation (TPP) has gained importance as a faster, more economical, and more effective alternative to traditional purification techniques. In this study, EPSs were extracted from grape waste using TPP with the thermophilic Bacillus licheniformis SO2 strain, which was isolated and identified in our laboratory. The antioxidant properties of the extracted polysaccharides were investigated using DPPH and ABTS analyses. TPP conditions were optimized using Response Surface Method (RSM) to obtain the highest yield. EPS was obtained under the following conditions: 40% ammonium sulfate, a homogenate/tert-butanol ratio of 1.0:1.25, and pH 7. Under these optimal conditions, EPS at a concentration of 1 mg/ml demonstrated 88.7% radical scavenging activity against DPPH radicals and 65.7% against ABTS radicals. Based on these data, it is shown that thermophilic, bacterially produced exopolysaccharides isolated using a TPP-based extraction method possess strong antioxidant potential. It is thought that these biomolecules could be used in future pharmaceutical and nutraceutical applications.