|Ziegelhoffer, Thomas - UNIVERSITY OF WISCONSIN|
|Austin-Phillips, Sandra - UNIVERSITY OF WISCONSIN|
Submitted to: Biochemical and Biophysical Research Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 23, 1999
Publication Date: N/A
Interpretive Summary: When phytase, an enzyme, is mixed with animal feed, it breaks down organically bound phosphorous in the gut and reduces the amount of phosphorous in animal manure. Without the addition of this enzyme in the feed for chicken, hog, and many other farm animals, the manure will have excess phosphorous-rich compounds in it. Thus, the nutrient rich manure becomes a potential problem for phosphate pollution. One microbial enzyme that can breakup organically bound phosphate is phytase. In this study, we have taken the gene of a fungal phytase and put it into tobacco leaves. We have shown here that when the gene for phytase is put in plants, the "foreign" protein behaves similarly. This is very encouraging because agriculturally important fungal genes now can be expressed in crop plants for overproduction. This is more so for an enzyme like phytase that will eventually be mixed with animal feed for animals like chicken, turkey, and pig. This research will benefit the animal feed industry and the soybean growers.
Technical Abstract: The phyA gene from Aspergillus ficuum coding for a 441 amino acid full-length phytase was expressed in Nicotiana tabacum (tobacco) leaves. The expressed phytase was purified to homogeneity using ion-exchange column chromatography. The purified phytase was characterized biochemically and its kinetic parameters determined. When the recombinant phytase was compared with its counterpart from Aspergillus ficuum for physical and enzymatic properties, it was found that catalytically the recombinant protein was indistinguishable from the native phytase. Except for a decrease in molecular mass, the overexpressed recombinant phytase was virtually the same as the native fungal phytase. While the temperature optima of the recombinant protein remain unchanged, the pH optima shifted from pH 5 to 4. The results are encouraging enough to open the possibility of over-expressing phyA gene from Aspergillus ficuum in other crop plants as an alternative means of commercial production of this important enzyme.