Process optimization and characterization of levan from Sporosarcina globispora MTCC 4776

Abstract This study aims to explore Sporosarcina globispora MTCC 4776 to produce levan using submerged fermentation. The assessment of carbon and nitrogen sources revealed that a moderate concentration of sucrose and tryptone improved levan production. Eight of the independent variables, concentration of sucrose, tryptone, CaCl₂·2H₂O, K₂HPO₄, MgSO₄·7H₂O, % of inoculum, incubation time and agitation speed was assessed with twelve experimental runs through Plackett–Burman design. Concentration of sucrose, tryptone and agitation speed were found to be significant. These factors were further optimized using Central Composite Design, yielding a maximum of 1.41 g/L of levan, which is a 6.2-fold increase compared to unoptimized conditions. The extracted levan was characterized for its structure and physicochemical properties by FTIR, 1 H/ 13 C-NMR, TGA/DTG, DSC, and XRD. These results confirmed the presence of a β-(2 → 6)- linked fructofuranosyl chain with excellent thermal stability and a semi-crystalline structure. In the future, studies on the purification and application of levan will be conducted to assess the sample’s potential.