Alcalase immobilization in iota-carrageenan-matrix hydrogel beads derived from the macroalga Solieria filiformis

This study aims to immobilize Bacillus licheniformis (Alcalase) protease in iota-carrageenan (ιCAR) matrix hydrogels via adsorption. CAR was extracted from macroalgae Solieria filiformis and used to produce hydrogels using Al^{3 +} as the gelling agent. Subsequently, enzyme immobilization was performed at 25ºC, for 120 min using particles of ∼2.0 mm diameter, varying the medium pH values (7.0, 8.0, and 9.0). The immobilization at pH 8.0 resulted in the biocatalyst with the highest immobilization yield (100 %), expressed activity (88.9 %), and mass activity (10.4 U/g) for 1.0 mg/g of enzyme loading. When using particles with different diameters (1.0, 2.0, and 3.0 mm), the best results were obtained using 1.0 mm particles. This permitted a 100 % immobilization yield, 95.8 % expressed activity, and high mass activity (11.2 U/g). The lyophilized biocatalyst presented varying macro-pore diameters, ranging from 21 to 126 µm. The immobilized biocatalyst was 11 times more stable than the soluble enzyme at 60ºC and pH 8.0 and presented > 80 % retained activity in the pH range 6.0-9.0.