A screening of 10 strains of Aspergillus for pellet formation and mycelia-associated β-xylosidase activity was performed in media containing glucose and glucose supplemented with methyl β-d-xylopyranoside. The aim was to produce an immobilized enzyme preparation. Three strains with high mycelia-associated β-xylosidase activity were investigated for enzyme leakage and enzyme stability:A. terreus QM 1991, A. phoenicis ATCC 13157, and A. phoenicis QM 329. The pellets of A. phoenicis QM 329 had the highest β-xylosidase activity (280 IU/g dry wt mycelia) after 333 h of incubation. From measurements of both cell-bound enzyme activity and the activity in solution, it could be concluded that for Aspergillus phoenicis QM 329 and ATCC 13157 the decrease in β-xylosidase activity bound to the pellets was owing to enzyme leakage. For Aspergillus terreus QM 1991, the decrease of pellet-bound β-xylosidase activity was the result of both leakage and enzyme deactivation at 50°C. β-Xylosidase in pellets of A. phoenicis QM329 hydrolyzes xylobiose and p-nitrophenyl β-d-xylopyranoside with the same rate of conversion.
- mycelial pellets
- xylobiose hydrolysis
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology
- Molecular Biology