Transgenic mice expressing bacterial phytase as a model for phosphorus pollution control.
We have developed transgenic mouse models to determine whether endogenous expression of phytase transgenes in the digestive tract of monogastric animals can increase the bioavailability of dietary phytate, a major but indigestible form of dietary phosphorus. We constructed phytase transgenes composed of the appA phytase gene from Escherichia coli regulated for expression in salivary glands by the rat R15 proline-rich protein promoter or by the mouse parotid secretory protein promoter. Transgenic phytase is highly expressed in the parotid salivary glands and secreted in saliva as an enzymatically active 55 kDa glycosylated protein. Expression of salivary phytase reduces fecal phosphorus by 11%. These results suggest that the introduction of salivary phytase transgenes into monogastric farm animals offers a promising biological approach to relieving the requirement for dietary phosphate supplements and to reducing phosphorus pollution from animal agriculture.
Golovan
S P
SP
Department of Microbiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Hayes
M A
MA
Phillips
J P
JP
Forsberg
C W
CW
D010832:6-Phytase / Q000235:genetics*; D000135:Acid Phosphatase / Q000235:genetics*; D000818:Animals; D015152:Blotting, Northern; D004591:Electrophoresis, Polyacrylamide Gel; D004787:Environmental Pollution / Q000517:prevention & control*; D029968:Escherichia coli Proteins; D005243:Feces / Q000737:chemistry; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D008372:Manure / Q000032:analysis; D051379:Mice; D008822:Mice, Transgenic / Q000502:physiology; D010306:Parotid Gland / Q000201:enzymology; D010758:Phosphorus / Q000378:metabolism*; D051381:Rats; D013363:Submandibular Gland / Q000201:enzymology
D029968:Escherichia coli Proteins; D008372:Manure; D010758:Phosphorus; D000135:Acid Phosphatase; D010832:6-Phytase; C406788:appA protein, E coli