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

Abstract

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 Bacillus licheniformis 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 Staphylococcus aureus and Pseudomonas aeruginosa, as well as prebiotic potential for Lactobacillus plantarum. 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.