Cost-effective production of high molecular weight dextran using sugarcane juice: statistical optimization and application to prepare support material for biofuel generation

The current study focuses on enhancing microbial dextran production using a renewable and cost-effective Saccharum officinarum juice medium (SOJM) feedstock and compares it with a chemically defined medium (CDM). The optimized medium variables using SOJM (sucrose: 200 g/L; yeast extract: 10 g/L; KH₂PO₄: 50 g/L; time: 2 d) and CDM (sucrose: 200 g/L; yeast extract: 40.5 g/L; KH₂PO₄: 50 g/L; time: 1 d) for predicting the dextran production were found to be 80 and 96 g/L, respectively. The economic productivity of produced dextran from SOJM and CDM was 0.06 and 0.18 $ dextran per $ nutrient per h, respectively. The functional, structural characteristics, and molecular mass distribution of the produced dextran using SOJM and CDM were analyzed using various characterization techniques. The average molecular mass of dextran using SOJM (before optimization: 2519.7 kDa; after optimization: 3474.3 kDa) is greater than that of CDM (before optimization: 2119.7 kDa; after optimization: 2884.2 kDa). These findings demonstrated that the optimization approach significantly enhanced both yield and average molecular mass using CDM and SOJM. Owing to its antioxidant activity, the produced dextran could be extensively employed in various healthcare applications. Furthermore, the produced dextran is involved in the preparation of an immobilization matrix with calcium alginate for the entrapment of cellulase. The prepared matrix (dex-cel-alg) exhibited greater immobilization efficiency (86.9%) than the alginate matrix (35.5%), illustrating its suitability for the hydrolysis of cellulose to fermentable sugars for biofuel applications.