IDENTIFICATION AND CLONING OF A 2ND PHYTASE GENE (PHYB) FROM ASPERGILLUS-NIGER (FICUUM)

An Aspergillus niger (ficuum) genomic DNA λEMBL3 library was probed with a 354-bp DNA fragment obtained by polymerase chain reaction of A. niger DNA with oligonucleotides based on partial amino acid sequence of a pH 2.5 optimum acid phosphatase. A clone containing a 1605 bp segment (phyB) encoding the 479 amino acid enzyme was isolated and found to contain four exons. Global alignment revealed 23.5% homology to Aspergillus niger phytase (PhyA); four regions of extensive homology were identified. Some of these regions may contain catalytic sites for phosphatase function. © 1993 Academic Press, Inc.