Immobilization of fungus Aspergillus sp. by a novel cryogel technique for production of extracellular hydrolytic enzymes

Abstract

Aerobic cells of a fungus isolate Aspergillus sp. CX-1 have been immobilized in macroporous cryoPAG and in different composite cryoPAGs — fibrous adjunct carriers. The productivity of the extracellular enzymes (exo-1.4-β-glucanase, endo-1.4-β-glucanase, β-glucosidase and xylanase), and the viability, growth and ultrastructure of the immobilized fungus have been studied. The enzyme activities and stability during long-term repeated batch cultivation in the immobilized fungus were higher than in free mycelia when batch cultivated. The fungus immobilized in the composite cryoPAG, containing polypropylene non-woven fabric, possessed the highest exo-1.4-β-glucanase activity, the longest durability of enzyme production (85 days) and the most reliable mechanical strength. The fungus immobilized in porous composite cryogel possessed a variety of advantages including easy control of cryogel porosity, improved mechanical strength and durability, simplicity of construction, high enzyme productivity and high stability.