A Potential Phosphate Crisis

Abelson, Philip H.

doi:10.1126/science.283.5410.2015

Cited by 278 publications

(137 citation statements)

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“…This is ecologically beneficial because P promotes eutrophication of fresh-water reserves (2) . The substrate, phytate, is present in all feedstuffs of plant origin predominantly as a Mg and K salt of phytic acid (myo-inositol hexaphosphate; IP 6 ), which may be represented as Mg 3 -K 6 -IP 6 ( 3) . Consequently, all practical pig and poultry diets contain variable concentrations of phytate, often in the order of 10 g/kg.…”

Section: Introductionmentioning

confidence: 99%

“…This is mainly due to the insolubility of mineral calcium phytate complexes at small-intestinal pH levels (4) in diets with conventional levels of Ca. Proximally, in the more acidic conditions of the stomach of pigs or the proventriculus and gizzard of poultry, phytate is relatively soluble and exogenous phytases have the capacity to hydrolyse IP 6 , at least partially at standard inclusion rates, thereby liberating inorganic P moieties. The enzymic degradation of phytate and the release of phytate-bound P, coupled with reductions in dietary P concentrations, combine to reduce P levels in excreta.…”

Section: Introductionmentioning

confidence: 99%

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Protein–phytate interactions in pig and poultry nutrition: a reappraisal

et al. 2012

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Protein–phytate interactions are fundamental to the detrimental impact of phytate on protein/amino acid availability. The inclusion of exogenous phytase in pig and poultry diets degrades phytate to more innocuous esters and attenuates these negative influences. The objective of the present review is to reappraise the underlying mechanisms of these interactions and reassess their implications in pig and poultry nutrition. Protein digestion appears to be impeded by phytate in the following manner. Binary protein–phytate complexes are formed at pH levels less than the isoelectric point of proteins and complexed proteins are refractory to pepsin digestion. Once the protein isoelectric points are exceeded binary complexes dissociate; however, the isoelectric point of proteins in cereal grains may be sufficiently high to permit these complexes to persist in the small intestine. Ternary protein–phytate complexes are formed at pH levels above the isoelectric point of proteins where a cationic bridge links the protein and phytate moieties. The molecular weights of protein and polypeptides in small-intestinal digesta may be sufficient to allow phytate to bind nutritionally important amounts of protein in ternary complexes. Thus binary and ternary complexes may impede protein digestion and amino acid absorption in the small intestine. Alternatively, phytate may interact with protein indirectly.Myo-inositol hexaphosphate possesses six phosphate anionic moieties (HPO42–) that have strong kosmotropic effects and can stabilise proteins by interacting with the surrounding water medium. Phytate increases mucin secretions into the gut, which increases endogenous amino acid flows as the protein component of mucin remains largely undigested. Phytate promotes the transition of Na+into the small-intestinal lumen and this suggests that phytate may interfere with glucose and amino acid absorption by compromising Na+-dependent transport systems and the activity of the Na pump (Na+-K+-ATPase). Starch digestion may be depressed by phytate interacting with proteins that are closely associated with starch in the endosperm of cereal grains. While elucidation is required, the impacts of dietary phytate and exogenous phytase on the site, rate and synchrony of glucose and amino acid intestinal uptakes may be of importance to efficient protein deposition. Somewhat paradoxically, the responses to phytase in the majority of amino acid digestibility assays in pigs and poultry are equivocal. A brief consideration of the probable reasons for these inconclusive outcomes is included in this reappraisal.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Protein–phytate interactions in pig and poultry nutrition: a reappraisal

et al. 2012

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“…This situation has arisen because soybeans, grains and other plant seeds are used as the primary protein source in the animal feed . Approximately 80% of the organic phosphate in these seeds resides in InsP 6 , but the digestive lumen of these animals contains little or no phytase activity (Abelson, 1999;Mullaney et al, 2000). Thus, nutritional requirements necessitate that inorganic phosphate be added to the feed.…”

Section: Introductionmentioning

confidence: 99%

Avian multiple inositol polyphosphate phosphatase is an active phytase that can be engineered to help ameliorate the planet's “phosphate crisis”

Cho

Choi

Darden

et al. 2006

Journal of Biotechnology

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Contemporary phytase research is primarily concerned with ameliorating the problem of inadequate digestion of inositol hexakisphosphate (phytate; InsP 6 ) in monogastric farm animal feed, so as to reduce the pollution that results from the high phosphate content of the manure. In the current study we pursue a new, safe and cost-effective solution. We demonstrate that the rate of hydrolysis of InsP 6 by recombinant avian MINPP (0.7 μmol/mg protein/min) defines it as by far the most active phytase found to date in any animal cell (the corresponding activity of recombinant mammalian MINPP is only 0.006 μmol/mg protein/min). Although avian MINPP has less than 20% sequence identity with microbial phytases, we create a homology model of MINPP in which it is predicted that the structure of the phytase active site is well-conserved. This model is validated by site-directed mutagenesis and by use of a substrate analogue, scyllo-InsP 6 , which we demonstrate is only a weak MINPP substrate. In a model chicken cell line, we overexpressed a mutant form of MINPP that is secretion-competent. This version of the enzyme was actively secreted without affecting either cell viability or the cellular levels of any inositol phosphates. Our studies offer a genetic strategy for greatly improving dietary InsP 6 digestion in poultry.

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“…Analysis of data collected over 14 years revealed that the usage of global P fertilizer considerably increased at a rate of about 357,000 t/annum (i.e., an annual increase of 2.4%) [12,13]. Experts agree that the world is facing serious P crisis [14,15] and that the global P reserve is not distributed uniformly [5]. Taken together, these issues constitute compelling evidence justifying a direct link between Pi availability and the overwhelming world food security in coming few years.…”

Section: Introductionmentioning

confidence: 99%

Phosphorus Transport in Arabidopsis and Wheat: Emerging Strategies to Improve P Pool in Seeds

et al. 2018

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Phosphorus (P) is an essential macronutrient for plants to complete their life cycle. P taken up from the soil by the roots is transported to the rest of the plant and ultimately stored in seeds. This stored P is used during germination to sustain the nutritional demands of the growing seedling in the absence of a developed root system. Nevertheless, P deficiency, an increasing global issue, greatly decreases the vigour of afflicted seeds. To combat P deficiency, current crop production methods rely on heavy P fertilizer application, an unsustainable practice in light of a speculated decrease in worldwide P stocks. Therefore, the overall goal in optimizing P usage for agricultural purposes is both to decrease our dependency on P fertilizers and enhance the P-use efficiency in plants. Achieving this goal requires a robust understanding of how plants regulate inorganic phosphate (Pi) transport, during vegetative growth as well as the reproductive stages of development. In this short review, we present the current knowledge on Pi transport in the model plant Arabidopsis thaliana and apply the information towards the economically important cereal crop wheat. We highlight the importance of developing our knowledge on the regulation of these plants' P transport systems and P accumulation in seeds due to its involvement in maintaining their vigour and nutritional quality. We additionally discuss further discoveries in the subjects this review discusses substantiate this importance in their practical applications for practical food security and geopolitical applications.

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A Potential Phosphate Crisis

Cited by 278 publications

References 0 publications

Protein–phytate interactions in pig and poultry nutrition: a reappraisal

Protein–phytate interactions in pig and poultry nutrition: a reappraisal

Avian multiple inositol polyphosphate phosphatase is an active phytase that can be engineered to help ameliorate the planet's “phosphate crisis”

Phosphorus Transport in Arabidopsis and Wheat: Emerging Strategies to Improve P Pool in Seeds

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