Phytic Acid Studies.

Phytic acid (inositol hexakisphosphate [InsP 6 ]) is the storage compound of phosphorus in seeds. As phytic acid binds strongly to metallic cations, it also acts as a storage compound of metals. To understand the mechanisms underlying metal accumulation and localization in relation to phytic acid storage, we applied synchrotron-based x-ray microfluorescence imaging analysis to characterize the simultaneous subcellular distribution of some mineral elements (phosphorus, calcium, potassium, iron, zinc, and copper) in immature and mature rice (Oryza sativa) seeds. This fine-imaging method can reveal whether these elements colocalize. We also determined their accumulation patterns and the changes in phosphate and InsP 6 contents during seed development. While the InsP 6 content in the outer parts of seeds rapidly increased during seed development, the phosphate contents of both the outer and inner parts of seeds remained low. Phosphorus, calcium, potassium, and iron were most abundant in the aleurone layer, and they colocalized throughout seed development. Zinc was broadly distributed from the aleurone layer to the inner endosperm. Copper localized outside the aleurone layer and did not colocalize with phosphorus. From these results, we suggest that phosphorus translocated from source organs was immediately converted to InsP 6 and accumulated in aleurone layer cells and that calcium, potassium, and iron accumulated as phytic acid salt (phytate) in the aleurone layer, whereas zinc bound loosely to InsP 6 and accumulated not only in phytate but also in another storage form. Copper accumulated in the endosperm and may exhibit a storage form other than phytate.

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“…Zn . cadmium, whereas Maddaiah et al (1964), using a different titration method, reported the stability order as Zn . Cu .…”

Section: Discussionmentioning

confidence: 99%

“…The stability of InsP 6 -metal complexes has been estimated by in vitro titration (Maddaiah et al, 1964;Vohra et al, 1965;Persson et al, 1998). The binding strength of InsP 6 with metal is stronger for Zn and Cu than for Fe, Mn, and Ca.…”

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confidence: 99%

Dynamic Changes in the Distribution of Minerals in Relation to Phytic Acid Accumulation during Rice Seed Development

et al. 2012

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“…Notionally, the phytate molecule carries a maximum of twelve negative charges and could potentially chelate six Ca atoms although the affinity of phytate is greater for certain other divalent cations, including zinc and copper (Maddaiah et al, 1964;Vohra et al, 1965). Nevertheless, Ca 2+ is a dominant cation in diets and consequently de novo formation of insoluble Ca-phytate complexes in the gut at conducive pH levels assumes importance (Wise, 1983;Angel et al, 2002).…”

Section: Introductionmentioning

confidence: 97%

Consequences of calcium interactions with phytate and phytase for poultry and pigs

2009

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“…This eliminates the need for external addition of phosphorous to the feed, which incurs costs and also contributes to environmental pollution [3,23,43]. Removal of phytate from the feed also has other advantages in terms of overcoming its negative nutritional eVects such as decrease in the bioavailability of vital minerals [20,21,27,30], impairing the function of digestive enzymes or decrease in the digestibility of feed protein [2,3,17]. For the phytase to be eVective, it needs to be thermostable enough to withstand the high temperatures used during feed preparation.…”

Section: Introductionmentioning

confidence: 99%

A thermostable phytase from Bacillus sp. MD2: cloning, expression and high-level production in Escherichia coli

Tran

Mamo

Mattìasson

et al. 2009

J Ind Microbiol Biotechnol

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Phytase is used as a feed additive for degradation of antinutritional phytate, and the enzyme is desired to be highly thermostable for it to withstand feed formulation conditions. A Bacillus sp. MD2 showing phytase activity was isolated, and the phytase encoding gene was cloned and expressed in Escherichia coli. The recombinant phytase exhibited high stability at temperatures up to 100 degrees C. A higher enzyme activity was obtained when the gene expression was done in the presence of calcium chloride. Production of the enzyme by batch- and fed-batch cultivation in a bioreactor was studied. In batch cultivation, maintaining dissolved oxygen at 20-30% saturation and depleting inorganic phosphate below 1 mM prior to induction by IPTG resulted in over 10 U/ml phytase activity. For fed-batch cultivation, glucose concentration was maintained at 2-3 g/l, and the phytase expression was increased to 327 U/ml. Induction using lactose during fed-batch cultivation showed a lag phase of 4 h prior to an increase in the phytase activity to 71 U/ml during the same period as IPTG-induced production. Up to 90% of the total amount of expressed phytase leaked out from the E. coli cells in both IPTG- and lactose-induced fed-batch cultivations.

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Phytic Acid Studies.

Cited by 102 publications

References 1 publication

Dynamic Changes in the Distribution of Minerals in Relation to Phytic Acid Accumulation during Rice Seed Development

Dynamic Changes in the Distribution of Minerals in Relation to Phytic Acid Accumulation during Rice Seed Development

Consequences of calcium interactions with phytate and phytase for poultry and pigs

A thermostable phytase from Bacillus sp. MD2: cloning, expression and high-level production in Escherichia coli

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