Isolation, Physicochemical Characterization, and Potential Bioactivities of Levan Produced by Thermostable Levansucrase from <i>Bacillus licheniformis</i> ATS95 Using Low-Cost Organic Solid Wastes

Organic solid waste presents viable and sustainable feedstock for the production of high-value biopolymers. Levan, a fructan, finds extensive applications in the food and healthcare sectors; however, its commercial production is hampered by prohibitive costs associated with sucrose. This study was conducted to find an eco-friendly, cost-effective, and sustainable approach to produce levan utilizing organic solid wastes. Thermophilic <i>Bacillus licheniformis</i> ATS95 was isolated and optimized for waste-based levan production. Characterization of carbohydrate polymers via scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, ¹³C NMR, and TOF-ESI-MS confirmed the presence of thermostable, crystalline, and amorphous high-molecular-weight levans. Functional assays revealed levan's strong emulsification index (54-56%), high antioxidant activity (91% DPPH, 84% ABTS), notable anti-inflammatory activity (53.62%), and good antibiofilm (47%) activity against <i>Staphylococcus aureus</i> and <i>Pseudomonas aeruginosa</i>, as well as prebiotic potential for <i>Lactobacillus plantarum</i>. The strain displayed notable levansucrase activity and stability, emphasizing its potential for sustainable waste valorization and promising applications in food preservation, healthcare, and environmental conservation.