Submitted to: Archives Of Microbiology
Publication Type: Review article
Publication Acceptance Date: 8/31/1996
Publication Date: N/A
Citation: Interpretive Summary: Interpretive summary is not required--review article.
Technical Abstract: A wild type strain of A. Niger NRRL 3135 produces the highest level of any phytase in a mineral salt. The strain produces two phytases one with pH optima at 2.5 and 5.5 (phyA) and one with an optimum at pH 2.0 (phyB). It produces a pH 6.0 optimum phosphatase that lacks phytase activity. The phytases were purified to homogeneity, characterized, sequenced and cloned. The sequences have been compared to each other, other phytases and to known phosphatases. Their homology has been determined. The active sites of phytases show remarkable homology to the active site residues of a member of a particular class of acid phosphatase known as histidine phosphatase.' The most conservative sequence is RHGXRXP. Phytase has been immobilized on various matrices. Commercial preparations of the cloned enzyme (phyA) are has been immobilized on various matrices. Commercial preparations of the cloned enzyme (phyA) are available. Phytase has also been cloned into tobacco and canola. The enzyme is localized in the seed and expressed at high levels. The efficacy of feeding phytase to poultry and swine has been established. The effect of feeding phytase to animals enables assimilation of the phosphate found in feed ingredients and diminishes the amount of phosphate in the manure and subsequently entering the environment.