title: Bioprocessing strategies for improving hen egg-white lysozyme (HEWL) production by recombinant Aspergillus niger HEWL WT-13-16.
abstract: Hen egg-white lysozyme (HEWL) production by recombinant Aspergillus niger HEWL WT-13-16 from a cDNA under the control of the A. niger glucoamylase promoter was used as a model system. The fungal mycelium was either immobilized on porous Celite 560 micro-carrier or grown in suspension as pelleted and dispersed forms. The objective was to reduce the protease activity that adversely affects the expressed HEWL. Free suspension culture at uncontrolled pH served as the benchmark. The control of pH during growth at pH 4.0 gave rise to a greater than five-fold reduction of protease activity in suspension culture. An additional 38.5% decrease in protease activity was achieved in mycelial-pellet cultures in comparison to a 40.9% decrease in protease activity obtained with Celite 560 beads in an airlift vessel at controlled pH. The specific HEWL yields were 5.8, 5.0 and 4.1 mg/g dry wt. for the free suspension, mycelial-pellet, and Celite-560-immobilized cultures, respectively.
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Gyamerah
authors.forename: G
authors.initials: G
authors.lastname: Merichetti
authors.forename: O
authors.initials: O
authors.lastname: Adedayo
authors.forename: J M
authors.initials: JM
authors.lastname: Scharer
authors.forename: M
authors.initials: M
authors.lastname: Moo-Young
mesh_terms: D000818:Animals; D001234:Aspergillus niger / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D019149:Bioreactors; D001709:Biotechnology; D018914:Cells, Immobilized; D002645:Chickens; D003470:Culture Media; D004274:DNA, Recombinant / Q000235:genetics / Q000302:isolation & purification; D007692:Diatomaceous Earth; D006863:Hydrogen-Ion Concentration; D009113:Muramidase / Q000096:biosynthesis* / Q000235:genetics; D010063:Ovum / Q000201:enzymology*; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics
chemical_list: D003470:Culture Media; D004274:DNA, Recombinant; D011994:Recombinant Proteins; D007692:Diatomaceous Earth; D009113:Muramidase