Enzyme-assisted extraction of fucoidan from Kjellmaniella crassifolia based on kinetic study of enzymatic hydrolysis of algal cellulose

Fucoidan extraction from Kjellmaniella crassifolia was enhanced through β-glucosidase fortified cellulase treatment. Kinetic study of the hydrolysis of isolated seaweed cellulose by commercial enzymes was carried out, and cellulolytic enzyme cocktail was optimized according to the degradation kinetics using response surface methodology for fucoidan extraction. Cellulose (9.88 wt%, d.b.) found in the seaweed was highly crystalline (CrI: 83.24 %). β-glucosidase apparently improved the affinity of the cellulolytic enzymes for the cellulose by eliminating cellobiose feedback inhibition. Treating the seaweed with 30 FPU cellulase supplemented with 286.64 CBU β-glucosidase per gram cellulose, followed by conventional ethanol precipitation, the fucoidan extraction yield based on seaweed feedstock dry matter reached 4.74 %. The total sugar content and sulfate content of the product reached 76.68 % and 22.83 %, respectively, with fucose accounting for 62.46 % of the total sugar. The product extracted under optimal conditions exhibited apparently concentration-dependent antioxidant activity, with IC50 values for DPPH, Hydroxyl and ABTS radical scavenging reaching 2.43 mg/mL, 1.02 mg/mL and 1.12 mg/mL, respectively. The results showed that the proposed enzymatic treatment based on cellulose hydrolysis kinetics effectively disrupted the cell wall and facilitated the release and extraction of fucoidan from the seaweed.