从土壤中筛选到产植酸酶的黑曲霉菌株Ａｓｐｅｒｇｉｌｌｕｓ ｎｉｇｅｒ ９６３，对其所产植酸的生理化性质研究表明其具有适合于在饲料中使用的优良性质它的酶活性最适温度为５５℃，最适ＰＨ值分别为ｐＨ１．８和５．７，并且ｐＨ１．８－５．７的范围内，植酸酶均能维持较高的酶活性。
Aspergillus niger 963 secreting phytase is isolated from soil . It is cultivated by a shaking method and phytase is pro - duced 165 U/mL . The phytase shows following properties . a ) Optimal pH values of the phytase for its activity are 1. 8 and 5 . 7 . b) Optimal temperature of the phytase for its activity is about 55 ℃ . The gene phy A2 encoding the phytase is cloned from A. niger 963 by polymerase chain reaction( PCR) . Nucleotide sequence analysis of phy A2 revealed that the presence of an open reading frame cod- ing for 467 amino acids and interrupted once by an intron of 102 bp in the 5' put of gene . The start codon is followed by a sequence coding for a putative signal peptide ( 19 amino acids in length ) . There are nine potential N - glycosylation sites in phytase . Compari- son with phytase gene phyA from A . niger ( ficuum) var . awamori shows 91 . 8% homology in nucleotides and 91. 6% in amino acids residues .
Journal of Agricultural Biotechnology