TY - JOUR
T1 - Purification and characterization of an extracellular phytase from Aspergillus niger ATCC 9142
AU - Walsh, Gary
AU - Casey, Anne
PY - 2003/1
Y1 - 2003/1
N2 - Extracellular phytase produced by Aspergillus niger ATCC 9142 was purified to homogeneity by employing an initial ultrafiltration step, followed by chromatography using ion exchange, gel filtration and chromatofocusing steps. The purified enzyme was an 84 kDa, monomeric protein. It possessed a temperature optimum of 65°C, and a pH optimum of 5.0. Km and Vmax values of 100 μM and 7 nmol/s, respectively, were recorded and these values fall well within the range of those previously reported for microbial phytases. Substrate specificity studies indicated that, while the enzyme could hydrolyse a range of non-phytate-based phosphorylated substrates, its preferred substrate was phytate. Phytase activity was moderately stimulated in the presence of Mg2+, Mn2+, Cu2+, Cd2+, Hg2+, Zn2+ and F- ions. Activity was not significantly affected by Fe2+ or Fe3+ and was moderately inhibited by Ca2+. The enzyme displayed higher thermostability at 80°C than did two commercial phytase products. Initial characterisation of the purified enzyme suggested that it could be a potential candidate for use as an animal feed supplement.
AB - Extracellular phytase produced by Aspergillus niger ATCC 9142 was purified to homogeneity by employing an initial ultrafiltration step, followed by chromatography using ion exchange, gel filtration and chromatofocusing steps. The purified enzyme was an 84 kDa, monomeric protein. It possessed a temperature optimum of 65°C, and a pH optimum of 5.0. Km and Vmax values of 100 μM and 7 nmol/s, respectively, were recorded and these values fall well within the range of those previously reported for microbial phytases. Substrate specificity studies indicated that, while the enzyme could hydrolyse a range of non-phytate-based phosphorylated substrates, its preferred substrate was phytate. Phytase activity was moderately stimulated in the presence of Mg2+, Mn2+, Cu2+, Cd2+, Hg2+, Zn2+ and F- ions. Activity was not significantly affected by Fe2+ or Fe3+ and was moderately inhibited by Ca2+. The enzyme displayed higher thermostability at 80°C than did two commercial phytase products. Initial characterisation of the purified enzyme suggested that it could be a potential candidate for use as an animal feed supplement.
KW - Animal feed
KW - Aspergillus niger
KW - Phytase
KW - Phytate
UR - http://www.scopus.com/inward/record.url?scp=0037209520&partnerID=8YFLogxK
U2 - 10.1016/S0960-8524(02)00145-1
DO - 10.1016/S0960-8524(02)00145-1
M3 - Article
C2 - 12653285
AN - SCOPUS:0037209520
SN - 0960-8524
VL - 86
SP - 183
EP - 188
JO - Bioresource Technology
JF - Bioresource Technology
IS - 2
ER -