Optimization and Partial Characterization of an Exopolysaccharide from Bacillus Rugosus L1C7T

Exopolysaccharides (EPS) are biological polymers secreted by microorganisms and are gaining attention due to their widespread use; however, their yield relies on the culture conditions. This study reports the EPS-producing bacterium Bacillus rugosus L1C7T for EPS production and describes the EPS, as well as its potential applications. Response surface methodology (RSM) was employed to optimize the growth medium and enhance EPS production to achieve this goal. The highest concentration of EPS (1.35 g l^- 1) was obtained in a culture medium that contained 11.25 g of NaCl, 6.25 g of K₂HPO₄, and a C/N ratio of 0.5. The EPS of B. rugosus L1C7T was analyzed using FT-IR, and the results revealed the presence of the following functional groups: O-H, C = O, C-C, C = C = C, N = C = S, C-O-C, N = C = O, and N = O. The ¹H NMR spectroscopy of the EPS revealed the presence of pyranose, 6-deoxy and acetyl sugars spectra. Additionally, this EPS demonstrated suitable radical scavenging capabilities, outstanding water solubility, water absorption, and oil absorption capacities of 125% and 65%, respectively. In addition, Thermo gravimetric analysis and Differential Scanning Calorimetric analysis found that the EPS of Bacillus rugosus L1C7T had multistep decomposition, and the glass transition temperature was 43.7 °C. The findings of this study suggested that the EPS of B. rugosus L1C7T has significant potential to be utilized in the food, pharmaceutical, and agricultural industries. Furthermore, the presence of these functional groups expands their potential for bioremediation.