Submitted to: Journal of Applied Microbiology
Publication Type: Review Article
Publication Acceptance Date: 6/22/2000
Publication Date: N/A
Technical Abstract: A huge market has developed for phytase as an animal feed additive. This happened in response to a complex of changes in agriculture that has resulted in expanded facilities to produce hogs and poultry cost- effectively using soybean and other plant meals as feed. However, without phytase most of the phytate phosphorus in this meal accumulates in their manure. As the number of animals produced has increased, the land's ability to hold this phosphorus from the manure has been exceeded. Nutrient runoff from the land has now been linked to a number of blooms of toxin-producing microbes that has attracted public concern engendering a greater interest in phytase as a means to reduce this phosphorus pollution. Aspergillus. niger phytase is now commercially produced and has been shown to be an effective feed additive to reduce phosphorus levels in animal manure. Phytases from a large number of organisms have been isolated and characterized. The best phytases belong to one class of enzyme, the histidine acid phosphatase (HAP). The X-ray crystal structure for two A. niger HAP phytases have been deduced and this information has been employed to understand the structure-function relationship in this enzyme. Research to improve the enzyme's heat tolerance, temperature and pH optima, substrate specificity, and stability is underway to further reduce the cost of this enzyme technology. Enzyme production techniques and improved enzymatic effects from synergistic interactions are also being evaluated. New markets and uses for phytase have also attracted added interest in this biocatalyst. All of these suggest that phytase research will continue to expand in the years to come.