Immobilization of Aspergillus nigerATCC 1015 on bionatural structures for lipase production

Abstract

Lipase of Aspergillus niger ATCC 1015 was immobilized onto matrices of a structural fibrous network (SFN) of pawpaw (Carica papaya) wood and vegetable sponge (VS) of (Luffa aegyptiaca) by physical entrapment through solid‐state fermentation. SFN‐ and VS‐immobilized lipases were characterized in terms of their operational and storage stability. The immobilizates were cross‐linked with ethanolic formaldehyde (EF), formaldehyde (F) and glutaraldehyde (GA). Ninety percent enzymatic activity was retained with GA as a coupling agent after 11 consecutive uses of SFN‐immobilized lipase, and after five, six, and four reuse times with EF, F, and uncross‐linked lipase, respectively. They showed different enzymatic characteristics (incubation time and operational stability) from those of VS‐immobilized enzyme. A relative activity above 75% was still achieved for the sample stored at 4°C and 50% at 28°C until fourth week of storage for both SFN‐ and VS‐immobilized lipases. In relation to the free biomass of A. niger ATCC 1015 hyphal cells, the SFN‐immobilized biomass with peak lipase activity (24.5 Ug−1) at day three resulted in 45.3% decrease in lipase production, whereas VS‐immobilized biomass with peak activity of 45.3 Ug−1 at day four resulted in 21.4% increase. This study revealed the potential of GA cross‐linked SFN as an excellent immobilizing agent.