Low Phytase Activity Research Articles

The Potential of Fermentation and Contamination of Teff by Soil to Influence Iron Intake and Bioavailability from Injera Flatbread.

The high phytic acid (PA) concentration in the diet based on teff injera is a likely contributing cause of iron deficiency in Ethiopia. We monitored PA during teff injera fermentation in 30 households in Debre Zeyit, Ethiopia and evaluated its influence on iron bioavailability, considering contaminant soil iron in teff flour. After fermentation (48h), mean PA concentration in injera batter decreased from 0.87 to 0.58 g/100 g dm (P < 0.001). Low phytase activity in teff flour (0.44 μmol phosphate/min/g) and a rapid drop in pH, indicated that PA degradation was driven by microbial phytases. The iron concentration in injera batter among the households ranged widely from 14.5-160.4 mg/100 g dm (mean: 34.7 mg/100 g dm) principally due to contamination with soil. Estimated intrinsic iron concentration of teff based on the strong correlation between total iron and aluminium concentrations (P < 0.001; aluminium concentrations in injera batter: 28.7-184.9 mg/100 g dm) was 4.4 mg/100 g dm, indicating that 86-97 % is extrinsic iron from soil. The median daily iron intakes from 3-day weighed food records in 10 young children were 18.9 mg/day including soil iron vs. 4.9 mg/day without soil iron (P < 0.01). The PA:iron molar ratios indicated low iron bioavailability from teff injera, particularly when soil iron was excluded. Traditional fermentation thus has a modest influence on PA levels and more complete degradation is needed to improve iron bioavailability. There is an urgent need to better understand the bioavailability of contamination iron from soil before considering national fortification or biofortification strategies in Ethiopia.

Phytate (Inositol Hexakisphosphate) in Soil and Phosphate Acquisition from Inositol Phosphates by Higher Plants. A Review.

Phosphate (P) fixation to the soil solid phase is considered to be important for P availability and is often attributed to the strong binding of orthophosphate anion species. However, the fixation and subsequent immobilization of inositolhexa and pentaphosphate isomers (phytate) in soil is often much stronger than that of the orthosphate anion species. The result is that phytate is a main organic P form in soil and the dominating form of identifiable organic P. The reasons for the accumulation are not fully clear. Two hypothesis can be found in the literature in the last 20 years, the low activity of phytase (phosphatases) in soil, which makes phytate P unavailable to the plant roots, and, on the other hand, the strong binding of phytate to the soil solid phase with its consequent stabilization and accumulation in soil. The hypothesis that low phytase activity is responsible for phytate accumulation led to the development of genetically modified plant genotypes with a higher expression of phytase activity at the root surface and research on the effect of a higher phytate activity on P acquisition. Obviously, this hypothesis has a basic assumption, that the phytate mobility in soil is not the limiting step for P acquisition of higher plants from soil phytate. This assumption is, however, not justified considering the results on the sorption, immobilization and fixation of phytate to the soil solid phase reported in the last two decades. Phytate is strongly bound, and the P sorption maximum and probably the sorption strength of phytate P to the soil solid phase is much higher, compared to that of orthophosphate P. Mobilization of phytate seems to be a promising step to make it available to the plant roots. The excretion of organic acid anions, citrate and to a lesser extend oxalate, seems to be an important way to make phytate P available to the plants. Phytase activity at the root surface seems not be the limiting step in P acquisition from phytate. Phytate is not only bound to inorganic surfaces in soil but can also be bound, similar to orthophosphate, to humic surfaces via Fe or Al bridges. Humic-metal-phytate complexes may be transported in the soil solution to the roots where hydrolysis and uptake of the liberated P may occur. Research on this topic is strongly required.

Construcción de un vector para la integración cromosomal de un gen de fitasa de Bacillus licheniformis

Phytases are a special class of phosphatases that catalyze the sequential hydrolysis of phytate. The inability of plants to utilize phosphorous from soil phytates is due to the low phytase activity in plant roots. Soil microorgan� microorganisms play an important role in the processes that affect the transformation of phosphate containing compounds. Many of them can solubilize phosphorus from phytates, by means of the liberation of phytases. This process allows the mobilization of phosphorus towards the plants and a better utilization of this nutrient. Nevertheless, many soil bacteria lack gene coding for these enzymes, which diminishes the availability of this element in soil. One alternative to obtain improved rhizobacteria in relation to their capacity to solubilize soil phytates is by their genetic transformation with genes that codify for those enzymes. In this work, the gene phyL from B. licheniformis was cloned into the suicide delivery vector pJMT6 (a derivative vector from the pUT/mini Tn5 system).

Phytase activity in rabbit cecal bacteria

The presence of phytase activity was demonstrated in 26 strains of rabbit cecal bacteria. In 25 strains a low phytase activity, 0.10-0.62 micromol phosphate released per min per mg protein, was found. High activity (2.61 micromol/min per mg protein) was found in the strain PP2 identified as Enterococcus hirae. Phytase activity was cell-associated, being higher in the cell extract than in the cell walls. Extracellular phytase activity and cell-associated phosphatase activity were not detected. Phytase activity was optimal around pH 5.0, which is below the physiological cecal pH range. The K (m) determined using the Lineweaver-Burk plot was 0.19 micromol/mL. Cations Fe(3+), Cu(2+) and Zn(2+) at 0.5 mmol/L decreased phytase activity in sonicated cells of E. hirae by 99.4, 90.7 and 96.5 %, respectively. In contrast, Mg(2+) increased activity by 11.0 %. Characteristics of E. hirae phytase (pH optimum, K (m), cation sensitivity) were similar to those of other bacterial phytases reported in the literature. Other bacteria with a high phytase activity may be present in the rabbit cecum but remain to be identified.

Phosphorus (from Different Phosphorus Sources) Utilisation in Piglets, and the Effect of the Addition of Phytase into the Feedstuff

The experiments were carried out in a 2x2 factorial treatments with three replicates, and were completed with 32P phosphorus metabolism measurement. Hungarian Large White x Dutch Landrace growing pigs with 15–18 kg starting live weight were involved in the experiment.The experimental scheme was the following:Diet consisted of maize and extracted soybean meal. Both components have high phytase content and low phytase activity. 1/a animals received their P-supply according to their needs and 1/b animals got 10% less than their actual P-need in the first part of the experiment.In the second part of the experiment both groups (2/a, 2/b) received identical P-supply and 500FTU/kg P supplementation. Apart from P- and phytase-supplementation, the piglets’ diet was identical.Total P digestibility was 52% without phytase supplementation, which increases by 4% when P was added according to need and by 12% increase of decreased P-supply. Digestibility of nutrients somewhat increased as effect of phytase supplementation. According to the results of 32P experiments, inorganic P digestibility of MCP was 82–90.8%, which decreases to 73.4–87.2% in case of phytase supplementation.Parallel with tendency, native P digestibility of the diet was 31.5–32.2%, which increased to 42.5–54.5% in the case of phytase supplementation.Results support the that inorganic P input can be decreased by phytase supplementation and as a consequence P output, the concept and environmental pollution can at the some time be decreased.

Degradation of phytate in the gut of pigs ‐ pathway of gastrointestinal inositol phosphate hydrolysis and enzymes involved

The present study gives an overview on the whole mechanism of phytate degradation in the gut and the enzymes involved. Based on the similarity of the human and pigs gut, the study was carried out in pigs as model for humans. To differentiate between intrinsic feed phytases and endogenous phytases hydrolysing phytate in the gut, two diets, one high (control diet) and the other one very low in intrinsic feed phytases (phytase inactivated diet) were applied. In the chyme of stomach, small intestine and colon inositol phosphate isomers and activities of phytases and alkaline phosphatases were determined. In parallel total tract phytate degradation and apparent phosphorus digestibility were assessed. In the stomach chyme of pigs fed the control diet, comparable high phytase activity and strong phytate degradation were observed. The predominant phytate hydrolysis products were inositol phosphates, typically formed by plant phytases. For the phytase inactivated diet, comparable very low phytase activity and almost no phytate degradation in the stomach were determined. In the small intestine and colon, high activity of alkaline phosphatases and low activity of phytases were observed, irrespective of the diet fed. In the colon, stronger phytate degradation for the phytase inactivated diet than for the control diet was detected. Phytate degradation throughout the whole gut was nearly complete and very similar for both diets while the apparent availability of total phosphorus was significantly higher for the pigs fed the control diet than the phytase inactivated diet. The pathway of inositol phosphate hydrolysis in the gut has been elucidated.

Lactobacillus plantarum phytase activity is due to non-specific acid phosphatase.

Microbial phytases suitable for food fermentations could be obtained from lactic acid bacteria isolated from natural vegetable fermentations. Phytase activity was evaluated for six lactic acid bacteria cultures. Although the highest activity was found for Lactobacillus plantarum, the phytase activity was very low. Further characterization of the enzyme with phytate-degrading activity showed a molecular weight of 52 kDa and an optimum activity at pH 5.5 and 65 degrees C. Enzyme activity was due to a non-specific acid phosphatase which had a higher hydrolysis rate with monophosphorylated compounds such as acetyl phosphate that could explain the low phytase activity.

Total phosphorus, phytate-phosphorus and phytase activity in plant feedstuffs

A total of 285 samples representing 51 feedstuffs used in Belgian feed-mills were quantitatively analysed for phytase activity, phytate-P and total P. It was concluded that the number of feedstuffs showing significant phytase activity (more than 100 units kg −1) is rather limited ( n = 13). Of the cereals analysed, only rye (5130 units kg −1), triticale (1688 units kg −1), wheat (1193 units kg −1) and barley (582 units kg −1) were rich in phytase. Wheat by-products, such as fine bran meal (4601 units kg −1) or pellets (2573 units kg −1)], middlings (4381 units kg −1), feed flour (3350 units kg −1) and bran (2957 units kg −1) were very phytase rich. Pelleted wheat fine bran samples were, on average, only 56% as active as non-pelleted wheat fine bran. Malt sprouts pellets (877 units kg −1) as well as corn distillers (385 units kg −1) also showed a moderate phytase activity. All other feedstuffs analysed showed zero or extremely low phytase activity. Phytase activity was not related to total P content or phytate-P content. A significant linear relationship was found between phytate-P and total P, for two feedstuff classes—wheat plus wheat by-products ( R 2 = 0.953; RSD = 0.060) and maize plus maize by-products ( R 2 = 0.928; RSD = 0.042)—but not for cereals or oil meals. Phytate-P content, as a percentage of total P content, was higher in cereals and in wheat by-products than in oil-seed meals and legume seeds. In malt sprouts, corn distillers and moist ensiled maize, phytate-P seems to be totally or partly hydrolysed as a result of processing or ensiling. In feedstuffs derived from roots and tubers, as well as in citrus pulp, cocoa shells, soyabean hulls, flax chaff, maize cob meal, dehydrated alfalfa and a dried mycelium sample, phytate-P was not detectable.

Phosphatase activity of four ectomycorrhizal fungi found in a Sitka spruce-Japanese larch plantation in Ireland

Ectomycorrhizal fungi (Paxillus involutus, Suillus grevillei and two unidentified basidiomycetes from excised Sitka spruce mycorrhizas) were isolated from stands of Sitka spruce either in monoculture or in mixture with Japanese larch in an Irish conifer plantation. They were grown for 35 d on modified Melin-Norkrans liquid medium containing ferric phytate as the phosphorus source. The cultures were then separated into wall- and membrane-bound, cytoplasmic and extracellular fractions and assayed for phosphatase. Wall- and membrane-bound fractions contained the most active acid phosphatase. The unidentified basidiomycetes showed a lower substrate affinity and higher velocity of reaction than P. involutus and S. grevillei. Wall- and membrane-bound and cytoplasmic phosphatase activities were optimum over a broad pH range (4·0–6·0). Various methods were used to release the wall-bound phosphatase and a high proportion (49–88%) appeared to be tightly held within the wall. Phosphatase released from the wall by sonication had a similar Km to wall-bound phosphatase but Vmax was lower. The use of a number of substrates demonstrated a high affinity for inorganic pyrophosphate and sodium β-glycerophosphate but a low phytase activity.