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Title: AVAILABILITY OF PHYTIC ACID COMPLEXES OF FERRIC AND FERROUS IRON TO ENZYMATIC DEPHOSPHORALATION BY ASPERGILLUS FICCUM

Author
item Heighton Davies, Lynne
item SIEFERT, RONALD - UNIV. OF MARYLAND
item Schmidt, Walter

Submitted to: American Society of Limnology and Oceanography
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2004
Publication Date: 6/18/2004
Citation: Heighton-Davies, L., Siefert, R.L., Schmidt, W.F. 2004. Availability of phytic acid complexes of ferric and ferrous iron to enzymatic dephosphoralation by aspergillus ficcum. American Society of Limnology And Oceanography Summer Meeting. Savannah, GA. June 13-18, 2004.

Interpretive Summary:

Technical Abstract: Phytic acid (inositol hexaphosphoric acid) is a major agricultural source of phosphorus (P) found in manures applied agriculturally to soils. However, little is known about the rates and conditions under which the biochemical dephosphoralation of phytate (the ionized form of phytic acid in soils) occurs and how this interacts with the inorganic P cycle in soils. Phytate forms strong complexes with ferric iron, and this complex may hinder the rate of dephosphoralation of phytic acid in the presence of Aspergillus ficcum, a common microbe that produces the enyzme phytase that catalyzes phytic acid dephosphoralation. The rates of enzymatic dephosphoralation of complexes of ferric phytate and ferrous phytate were investigated in this study. Aspergillus ficcum was added to pH 4.5 solutions of phytate containing either of the two oxidation states of iron respectively. Nitrogen gas was used to prevent oxidation of ferrous to ferric iron. Concentrations of inorganic phosphorus were measured colorimetrically by the ascorbic acid, molybdate method. The results of these studies will be presented together with the implications to the phosphorus cycle in soils.