Peniophora Lycii Research Articles

Comparative Analysis of Peniophora lycii and Trametes hirsuta Exoproteomes Demonstrates "Shades of Gray" in the Concept of White-Rotting Fungi.

White-rot basidiomycete fungi are a unique group of organisms that evolved an unprecedented arsenal of extracellular enzymes for an efficient degradation of all components of wood such as cellulose, hemicelluloses and lignin. The exoproteomes of white-rot fungi represent a natural enzymatic toolbox for white biotechnology. Currently, only exoproteomes of a narrow taxonomic group of white-rot fungi—fungi belonging to the Polyporales order—are extensively studied. In this article, two white-rot fungi, Peniophora lycii LE-BIN 2142 from the Russulales order and Trametes hirsuta LE-BIN 072 from the Polyporales order, were compared and contrasted in terms of their enzymatic machinery used for degradation of different types of wood substrates—alder, birch and pine sawdust. Our findings suggested that the studied fungi use extremely different enzymatic systems for the degradation of carbohydrates and lignin. While T. hirsuta LE-BIN 072 behaved as a typical white-rot fungus, P. lycii LE-BIN 2142 demonstrated substantial peculiarities. Instead of using cellulolytic and hemicellulolytic hydrolytic enzymes, P. lycii LE-BIN 2142 primarily relies on oxidative polysaccharide-degrading enzymes such as LPMO and GMC oxidoreductase. Moreover, exoproteomes of P. lycii LE-BIN 2142 completely lacked ligninolytic peroxidases, a well-known marker of white-rot fungi, but instead contained several laccase isozymes and previously uncharacterized FAD-binding domain-containing proteins.

Mycofloristic Studies on Wood Decaying Corticioid Fungi From Kullu District (Himachal Pradesh): Some New Additions

Coricioid fungi or the Corticiums form an important group of wood decayers in the forest ecosystem. These fungi plat a vital role in the recycling of carbon because of their unique ability to secreting lignin and cellulose decaying enzymes. Majority of these are saprophytic and a few have the ability to parasitize different tree species. During the exhaustive mycofloristic exploration of different parts of Kullu district of Himachal Pradesh some interesting specimens of wood decaying corticioids were collected and studied for their macro and micromorphological details. Based on macro and m microscopic details these were identified as five corticioid species ( Peniophora lycii , Scytinostroma ahmadii , Scytinostroma aluta , Stereum insignitum and Stereum thindii ). Among these species, Peniophora lycii and Stereum insignitum , the lignin decaying fungi, are described as new records for India and Stereum thindii is reported for the first time from Himachal Pradesh. All the five species are also the new additions to the mycoflora of Kullu district.

Characterization of the complete mitochondrial genome of Peniophora lycii (Russulales: Peniophoraceae) with its phylogenetic analysis

Peniophora lycii is a resupinate lichen-like species distributed all over the world. In the present study, we sequenced and assembled the complete mitochondrial genome of Peniophora lycii. The size of the mitochondrial genome of P. lycii was 38,296 bp, with a GC content of 25.89%. Twenty protein-coding genes, 2 ribosomal RNA genes, and 24 transfer RNA genes were identified in the mitochondrial genome of P. lycii. Phylogenetic analysis based on combined mitochondrial gene dataset indicated that the mitochondrial genome of P. lycii exhibited a close relationship with that of Heterobasidion irregulare.

Purification and Characterization of Two Novel Laccases from Peniophora lycii.

Although, currently, more than 100 laccases have been purified from basidiomycete fungi, the majority of these laccases were obtained from fungi of the Polyporales order, and only scarce data are available about the laccases from other fungi. In this article, laccase production by the white-rot basidiomycete fungus Peniophora lycii, belonging to the Russulales order, was investigated. It was shown that, under copper induction, this fungus secreted three different laccase isozymes. Two laccase isozymes—Lac5 and LacA—were purified and their corresponding nucleotide sequences were determined. Both purified laccases were relatively thermostable with periods of half-life at 70 °C of 10 and 8 min for Lac5 and LacA, respectively. The laccases demonstrated the highest activity toward ABTS (97 U·mg−1 for Lac5 and 121 U·mg−1 for LacA at pH 4.5); Lac5 demonstrated the lowest activity toward 2,6-DMP (2.5 U·mg−1 at pH 4.5), while LacA demonstrated this towards gallic acid (1.4 U·mg−1 at pH 4.5). Both Lac5 and LacA were able to efficiently decolorize such dyes as RBBR and Bromcresol Green. Additionally, phylogenetic relationships among laccases of Peniophora spp. were reconstructed, and groups of orthologous genes were determined. Based on these groups, all currently available data about laccases of Peniophora spp. were systematized.

Low digestibility of phytate phosphorus, their impacts on the environment, and phytase opportunity in the poultry industry

Phosphorus is anessential macro-mineral nutrient for poultry, needed for the body growth, development of bones, genomic function, good quality flesh, and eggs production. The imbalance of organic phosphorus sources in the diet mostly affect the phosphorus digestibility, reduces the poultry performance and health, and increases the environmental pollution burden. A study was reviewed to estimate the low phytate phosphorus digestibility of ingredients in poultry diet and their impacts on environmental ecosystem and opportunity of phytase supplementation. Plant ingredients mostly used in poultry diets are rich in phytate phosphorus. The phytate phosphorus digestibility and utilization is low in the gut of birds which leads to decrease other nutrients digestibility and increase excessive excretion of phosphorus with additional nutrients in the manure. When that manure applied to the lands containing excessive residual phosphorus and additional nutrients which pollute soil, groundwater disturbed the entire ecosystem. This issue is developed by poultry due to lack of digestive enzyme phytase which promotes the phytate phosphorus during digestion and reduces the excessive losses of phosphorus in excreta. To overcome this matter, the addition of mostly exogenous phospho-hydrolytic phytase enzymes in the diet, i.e. Escherichia coli, Peniophora lycii, Aspergillus niger, and Ficum, are the possible ways to increase the digestibility and utilization of phytate phosphorus and promote the stepwise release of phosphorus from phytate and significantly decrease phosphorus excretion. The aim of this review is to highlight the role of phytase supplementation in the poultry feeding, improvement of phytate phosphorus digestibility with performance, and reduction of phosphorus pollution from the environment.

Phosphorus acquisition by citrate- and phytase-exuding Nicotiana tabacum plant mixtures depends on soil phosphorus availability and root intermingling.

Citrate and phytase root exudates contribute to improved phosphorus (P) acquisition efficiency in Nicotiana tabacum (tobacco) when both exudates are produced in a P deficient soil. To test the importance of root intermingling in the interaction of citrate and phytase exudates, Nicotiana tabacum plant-lines with constitutive expression of heterologous citrate (Cit) or fungal phytase (Phy) exudation traits were grown under two root treatments (roots separated or intermingled) and in two soils with contrasting soil P availability. Complementarity of plant mixtures varying in citrate efflux rate and mobility of the expressed phytase in soil was determined based on plant biomass and P accumulation. Soil P composition was evaluated using solution 31 P NMR spectroscopy. In the soil with limited available P, positive complementarity occurred in Cit+Phy mixtures with roots intermingled. Root separation eliminated positive interactions in mixtures expressing the less mobile phytase (Aspergillus niger PhyA) whereas positive complementarity persisted in mixtures that expressed the more mobile phytase (Peniophora lycii PhyA). Soils from Cit+Phy mixtures contained less inorganic P and more organic P compared to monocultures. Exudate-specific strategies for the acquisition of soil P were most effective in P-limited soil and depended on citrate efflux rate and the relative mobility of the expressed phytase in soil. Plant growth and soil P utilization in plant systems with complementary exudation strategies are expected to be greatest where exudates persist in soil and are expressed synchronously in space and time.

Antibacterial activity of two isolated endophytic extracts assosiated with Indonesian mangrove plant Rhizophora mucronata

Endophytic fungi are microorganisms reside in the living tissues of the host plant. This fungi can contribute to provide protection to the host from the infection caused by another microorganism. The one reasonable strategy to discover a new antibacterial agent from endophytic fungi are from the plant which lived in special condition such Rhizophora mucronata . The aim of this research is to determine antibacterial activity of the endophytic fungi extracts assosiated with Rhizophora mucronata from Sagara anakan. The isolated endophytic fungi was identified as Neopestalotiopsis sp. and Peniophora lycii using molecular analysis method. The antibacterial activity was carried out by using microdillution method. The antibacterial properties from mycelium extracts showed moderate to low antibacterial activity with Minimum Inhibitory Consentration (MIC) values of 125-500 µg mL -1 against Eshcerichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 bacteria. The n -hexane extract of both endophytic fungi shows the strongest antibacterial activity against Escherichia coli with MIC values of 125 µg mL -1

Performance of Microbial Phytases for Gastric Inositol Phosphate Degradation

Microbial phytases catalyze dephosphorylation of phytic acid, thereby potentially releasing chelated iron and improving human iron absorption from cereal-based diets. For this catalysis to take place in vivo, the phytase must be robust to low pH and proteolysis in the gastric ventricle. This study compares the robustness of five different microbial phytases, evaluating thermal stability, activity retention, and extent of dephosphorylation of phytic acid in a simulated low-pH/pepsin gastric environment and examines secondary protein structural changes at low pH via circular dichroism. The Peniophora lycii phytase was found to be the most thermostable, but the least robust enzyme in gastric conditions, whereas the Aspergillus niger and Escherichia coli phytases proved to be most resistant to gastric conditions. The phytase from Citrobacter braakii showed intermediate robustness. The extent of loss of secondary structure at low pH correlated positively with the extent of activity loss at low pH.

Organic Anion–Driven Solubilization of Precipitated and Sorbed Phytate Improves Hydrolysis by Phytases and Bioavailability to Nicotiana tabacum

Improved plant access to native soil phosphorus (P) species such as phytate (metal ion derivatives of myo-inositol hexakisphosphate (IHP)) could minimize agricultural dependence on nonrenewable mineral phosphates and reduce surface water pollution. Nicotiana tabacum plant lines with unique organic anion (OA) and phytase production patterns were used to investigate the effect of OA-driven solubilization on the bioavailability of precipitated and sorbed IHP. Organic anions released IHP sorbed to goethite (Gt) by chelation or reductive dissolution mechanisms in the order: ascorbate > citrate > oxalate > pyruvate > acetate. Transgenic tobacco overexpressing Peniophora lycii phytase (PHY) and a MATE-type citrate transporter (CIT) exuded 2.2- to 2.6-fold higher OA compared with that of wild-type plants. The PHY plants had 33-fold higher exudate phytase activity (6.0 × 10−2 nkat plant−1 day−1) compared with those of wild-type and CIT plants, produced the largest zone of iron-IHP hydrolysis in agar media, and incorporated the most shoot P (2.3 μg) when grown on Gt-IHP. Plants grown on IHP at 2× Gt saturation (0.26 mmol/L) were 10-fold higher in shoot P compared with the 1× Gt condition (0.13 mmol/L IHP) with PHY plants approaching excess P status (1 % shoot P). The addition of Gt diminished shoot P in plants grown without P (−70 to −80 %) and with phosphate (−50 %) or IHP (−100 %); the exception was the high citrate–exuding plant line (21 nmol citrate plant−1 day−1), for which phosphate uptake was only 20 % reduced. Plant OA production mitigates P inhibition by Gt when weakly sorbing phosphate species are supplied or when high phytase production by plants can maximize the hydrolysis of IHP.

Scientific Opinion on Ronozyme®P (6-phytase) as feed additive for chickens and turkeys for fattening, laying hens, and piglets (weaned), pigs for fattening and sows (poultry and pigs)

Ronozyme® P/Bio-Feed® Phytase/ZY® Phytase is a 6-phytase produced by Aspergillus oryzae carrying a gene coding for phytase from Peniophora lycii. The safety of the genetic modification of the current production strain has been previously established by EFSA in 2004. The product is available in two forms: granulate and liquid, providing 5000 FYT/g and 20000 FYT/g, respectively. The liquid and solid forms of the additive are considered to be equivalent when used to deliver the same enzyme levels. Based on tolerance studies performed in chickens and turkeys for fattening, laying hens, ducks, piglets, pigs for fattening and sows, the FEEDAP Panel concludes that the additive is safe for those target species at the maximum proposed dose of 1000 FYT/kg complete feed. The FEEDAP Panel considers that these conclusions can be extended to all poultry (fattening and laying) and porcine species (growing and breeding) at the same maximum dose. The data previously assessed are considered to provide sufficient evidence that this product presents no risks for the consumer, user or the environment. The data provided allow drawing conclusions on the efficacy of the additive when supplemented to diets deficient in available P at the level of 250 FYT/kg complete feed for chickens and turkeys for fattening, 300 FYT/kg for laying hens, 500 FYT/kg for piglets and pigs for fattening and 750 FYT/kg for sows. These conclusions can be extended to the corresponding minor species.

Apparent nutrient and mineral digestibility in growing–finishing pigs fed phosphorus reduced diets supplemented with benzoic acid and phytase

In a study with 32 growing–finishing crossbred gilts (26–109 kg BW) the effects of benzoic acid and phytase ( Peniophora lycii) on nutrient digestibility in P reduced diets was examined. All animals were restrictively fed one of four experimental diets: control diet (CC) without any supplementation, control diet with 0.5% benzoic acid (CB), phytase diet (750 IU/kg,) without benzoic acid (PhyC) and phytase diet with 0.5% benzoic acid (PhyB). Total P (digestible P) content of the control diets was 4 g/kg (1.43 g/kg). In the grower period a negative interaction of benzoic acid × phytase ( p < 0.01) on apparent crude protein and energy digestibility was observed. In the finisher period both additives increased digestibility of P by 12% ( p < 0.02). Phytase improved Ca digestibility in both fattening periods (+ 13%, p < 0.05). In the finisher period an interaction of benzoic acid × phytase ( p < 0.01) reduced Ca digestibility from 0.62 in diet PhyC to 0.54 in diet PhyB. The results of this study indicate that the combination of benzoic acid and phytase in P reduced diets can adversely affect apparent nutrient and mineral digestibility. So far, the underlying mechanisms remain unclear.

Effects of phytase and 25-hydroxyvitamin D3 inclusions on the performance, mineral balance and bone parameters of grower–finisher pigs fed low-phosphorus diets

Two experiments, a performance experiment and a mineral balance study, were conducted on grower–finisher pigs (42 to 101 kg live weight) to investigate the effects of Peniophora lycii phytase enzyme and 25-hydroxyvitamin D3 (25-OHD3) on growth performance, carcass characteristics, nutrient retention and excretion, and bone and blood parameters. The two experiments were designed as a 2 × 2 factorial (two levels of phytase and two levels of 25-OHD3). The four diets were T1, low-phosphorous diet; T2, T1 + phytase; T3, T1 + 25-OHD3 and T4, T1 + phytase + 25-OHD3 diet. In all, 25 μg of 25-OHD3 was used to replace 1000 IU of vitamin D3 in diets T3 and T4. Diets were pelleted (70°C) and formulated to contain similar concentrations of energy (13.8 MJ DE/kg), lysine (9.5 g/kg) and digestible phosphorus (P; 1.8 g/kg). Neither the inclusion of phytase nor 25-OHD3 in the diet had any effect on pig performance. There was an interaction between phytase and 25-OHD3 on calcium (Ca) and P retention (P < 0.01) and on the apparent digestibility of ash (P < 0.01), P (P < 0.001) and Ca (P < 0.001). Pigs offered phytase diets only, had a higher retention of Ca and P and digestibility of ash (P < 0.01), P (P < 0.001) and Ca (P < 0.01) compared with pigs offered unsupplemented diets. However, when the combination of phytase and 25-OHD3 were offered, no effects were detected compared with 25-OHD3 diets only. Pigs fed phytase diets had higher bone ash (P < 0.01), bone P (P < 0.01) and bone Ca (P < 0.05) concentrations compared with pigs offered non-phytase diets. In conclusion, pigs offered phytase diets had a significantly increased bone ash, Ca and P than pigs offered unsupplemented phytase diets. However, there was no advantage to offering a combination of phytase and 25-OHD3 on either bone strength or mineral status compared to offering these feed additives separately.

Interrelationship of Steric Stabilization and Self-Crowding of a Glycosylated Protein

In the eukaryotic cell, protein glycosylation takes place in the crowded environment of the endoplasmatic reticulum. With the purpose of elucidating the impact of high concentration on the interactions of glycoproteins, we have conducted a series of small-angle x-ray scattering experiments on the heavily glycosylated enzyme Peniophora lycii phytase (Phy) and its deglycosylated counterpart (dgPhy). The small-angle x-ray scattering data were analyzed using an individual numerical form factor for each of the two glycoforms combined with two structure factors, a hard sphere and a screened coulomb potential structure factor, respectively, as determined by ab initio analysis. Based on this data analysis, three main conclusions could be drawn. First, at comparable protein concentrations (mg/ml), the relative excluded volume of Phy was ∼75% higher than that of dgPhy, showing that the glycans significantly increase excluded-volume interactions. Second, the relative excluded volume of dgPhy increased with concentration, as expected; however, the opposite effect was observed for Phy, where the relative excluded volume decreased in response to increasing protein concentration. Third, a clear difference in the effect of salinity on the excluded-volume interactions was observed between the two glycol forms. Although the relative excluded volume of dgPhy decreased with increasing ionic strength, the relative excluded volume of Phy was basically insensitive to increased salinity. We suggest that protrusion forces from the glycans contribute to steric stabilization of the protein, and that glycosylation helps to sustain repulsive electrostatic interactions under crowded conditions. In combination, this aids in stabilizing high concentrations of glycosylated proteins.

Sterols and lignin in Eucalyptus globulus Labill. wood: Spatial distribution and fungal removal as revealed by microscopy and chemical analyses

Abstract Wood decay experiments were carried out aiming at the selective removal of lipophilic compounds with selected basidiomycetes isolated from Eucalyptus globulus plantations in Uruguay: Dendrophora albobadia, Lentinus tigrinus, Peniophora cinerea, Peniophora lycii, and Phanerochaete crassa. Localization and composition of lipophilic compounds and lignin of E. globulus were determined by gas chromatography-mass spectrometry, fluorescence microscopy using filipin staining, confocal laser scanning microscopy (CLSM), and low temperature scanning electron microscopy. Free and esterified sterols, mainly sitosterol, were the predominant lipophilic compounds in the control wood. Sterols were present in ray parenchyma cells, together with polyphenols, and in vessels. This confirms earlier observations indicating that these cell types are the principal source of lipophilic extractives involved in pitch problems during pulping and bleaching. Sterols are also present in the vestures of fiber and vessel pits. Different fungal degradation patterns of E. globulus wood were determined. P. lycii showed the highest specificity for lignin degradation during short incubation time together with considerable sterol removal capacity. Ray parenchyma cells and their lumen deposits were strongly degraded by P. lycii. Eucalypt lignin located in vessel walls and fiber cell corners was more resistant to fungal attack, as revealed by CLSM. The initial decay stage of L. tigrinus was restricted to vessels and tyloses where the sterol compounds were removed.

Peniophora lycii phytase is stabile and degrades phytate and solubilises minerals in vitro during simulation of gastrointestinal digestion in the pig

Microbial phytases (EC 3.1.3) are widely used in diets for monogastric animals to hydrolyse phytate present in the feed and thereby increase phosphorus and mineral availability. Previous work has shown that phytate solubility is strongly affected by calcium in the feed and by pH in the gastrointestinal (GI) tract, which may have an effect on phytase efficacy. An in vitro model simulating the GI tract of pigs was used to study the survival of Peniophora lycii phytase and the effect of the phytase on phytate degradation, inositol phosphate formation and mineral solubilisation during in vitro digestion of a 30:70 soybean meal/maize meal blend with different calcium levels. The phytase retained 76 and 80% of its initial activity throughout the gastric in vitro digestion. Total phytate hydrolysis by P. lycii phytase was in the same range at total calcium levels of 1.2 and 6.2 mg g(-1) dry matter (DM), despite very large differences in phytate solubility at these calcium levels. However, at 11.2 and 21.2 mg Ca g(-1) DM, phytate hydrolysis was significantly lower. The amount of soluble mineral was generally increased by P. lycii phytase. Stability of P. lycii phytase during gastric digestion was not found to be critical for phytate hydrolysis. Furthermore, original phytate solubility was not an absolute requirement for phytate degradation; phytate solubility seemed to be in a steady state, allowing insoluble phytate to solubilise as soluble phytate was degraded. This is new and interesting knowledge that adds to the current understanding of phytate-phytase interaction. Copyright © 2007 Society of Chemical Industry.

Glycoprotein-surfactant interactions: A calorimetric and spectroscopic investigation of the phytase-SDS system

The interactions of sodium dodecyl sulfate (SDS) and two glyco-variants of the enzyme phytase from Peniophora lycii were investigated. One variant (Phy) was heavily glycosylated while the other (dgPhy) was enzymatically deglycosylated. Effects at 24 °C of titrating SDS to Phy and dgPhy were studied by Isothermal Titration Calorimetry (ITC) and Synchrotron Radiation Circular Dichroism (SRCD) spectroscopy. Comparisons of results for the two variants were used to elucidate glycan–surfactant interrelationships. The CD spectra suggested that both the native and the SDS-denatured states of the two variants were mutually similar, and hence that the denaturation process was structurally equivalent for the two glyco-variants. The denatured state was far from fully unfolded and probably retained a substantial content of native-like structure. Furthermore, it was found that the glycans brought about only a small increase in the resistance towards SDS induced denaturation. The SDS concentration required to denature half of the protein molecules differed less than 1 mM for the two variants. The affinity for SDS of both variants was unusually low. The amount of bound SDS (w/w) at different stages of the binding isotherm was 3–10 times lower than that reported for the most previously investigated globular proteins. Analysis of the relative affinity of the glycan and peptide moieties suggested that the carbohydrates bind much less surfactant. At saturation, glycans adsorbed about half as much SDS (in g/g) as the peptide moiety of Phy and about five times less than average proteins.

Comparison of different levels and sources of microbial phytases

Abstract Phytases catalyse the hydrolysis of phytate rendering phosphorus (P) available for absorption. Endogenous plant phytases are to some extent present in cereals (depending on species and varieties) while microbial phytases are added to cereal based diets to increase the digestibility of phytate bound P. The present study compared two different microbial phytases. The basal diet was composed of wheat, barley, soybean and rapeseed meal without feed phosphate. The diet was initially expanded, pelleted at 90 °C and crumbled. Phytases were added at 250, 500 and 750 FTU kg− 1 diet (Aspergillus niger; Phytase 1) and 375 and 750 FYT kg− 1 diet (Peniophora lycii; Phytase 2). The experiment comprised 6 treatment groups of 6 pigs each kept in metabolism crates and fed one of the 5 test diets or a diet with no added microbial phytase. The diets were fed for 12 days, 5 days for adaptation and 7 days for total collection of faeces and urine. Phosphorus digestibility of the basal diet averaged 43% and increased to 55, 61 and 66% following addition of 250, 500 and 750 FTU/kg of Phytase 1 and 54 and 60% following addition of 375 and 750 FYT/kg of Phytase 2, respectively. In conclusion, equivalent effects were obtained when Phytase 2 was given at 1.5 times the doses of Phytase 1.

Effects of Various Phytase Concentrations in Diets with Low-phytate Corn on Broiler Chick Performance and Nutrient Use

Research indicates a reduction in phosphorus content of broiler excreta with the supplementation of phytase to corn-soybean meal based diets or with the use of Low Phytate Corn (LPC). This study examined how broiler chicks are impacted by phytase supplementation to a LPC [0.136% Phytate Phosphorus (PP) by analysis] based diet. Different dietary inclusion levels from a 2,500 or a 5,000 FYT/g of Peniophora lycii phytase product were used as experimental treatments. Following a six day pretest, 576 broiler chicks were randomly assigned to one of 12 dietary treatments, using eight diet replicates and six birds per cage. Live performance, tibia ash, mineral digestibility and apparent metabolizable energy were determined. The percent of phosphorus that may have been spared due to each phytase treatment was calculated using response curves created with increasing levels of monocalcium phosphate. Results demonstrated that phytase supplementation to a LPC based diet had a positive impact on broiler chick growth. However, this impact is expressed to a lesser extent than would be expected for normal corn. In addition, phytase efficacy did not vary based on the concentration of phytase product, likely due to adequate mix uniformity.

Differential interaction of Aspergillus niger and Peniophora lycii phytases with soil particles affects the hydrolysis of inositol phosphates

The effect of the soil environment on the mobility, stability and catalytic activity of phytase from two sources was compared, as these factors have important implications for the efficacy of enzyme function in soil. Phytase from an ascomycete fungus ( Aspergillus niger) and a basidiomycete fungus ( Peniophora lycii) was added to soil suspensions from three contrasting soils and activities in the solution and solid phase were monitored. The two enzymes were compared because the P. lycii phytase was known to have greater specific activity and a more acidic isoelectric point (pI) than A. niger and therefore predicted to have different adsorption characteristics. When added to soil suspensions buffered at pH 7.5, both phytases remained in solution in all of the soils. In contrast at near natural soil pH (pH 5.5), only the P. lycii phytase remained in solution, while the A. niger phytase was rapidly adsorbed to the soil solid phase. The extent of this adsorption was reduced, however, in a soil-dependent manner by prior addition of bovine serum albumin (BSA) to the soil suspensions. At the natural pH of the soil, the stability of the P. lycii phytase in soil solution was improved under sterile conditions, whereas degradation of the A. niger phytase was unaffected. Subsequently, P. lycii phytase was shown to be more effective at hydrolysing myo-inositol hexakisphosphate added to the soil. Moreover, the P. lycii phytase also hydrolysed more organic phosphate that was endogenous to a range of soils. This research indicates that the physicochemical properties of fungal phytases affect their mobility and temporal stability and their capacity to hydrolyse inositol phosphates in soil environments.

Phytase effects on the efficiency of utilisation and blood concentrations of phosphorus and calcium in Pekin ducks

1. The objective was to study the effects of a supplementation of a 6-phytase derived from the Peniophora lycii gene in the White Pekin duck. 2. In two balance studies, low-phosphorus (P) diets consisting mainly of maize, solvent extracted soybean meal and solvent extracted sunflower meal were supplemented with phytase up to concentrations of 1500 U/kg (Study 1) or 2000 U/kg (Study 2). Each diet (phytase level) was fed to 8 to 10 individually penned ducks. The intake and excretion of each animal was measured for 5 consecutive days when ducks were in their third week of life. Responses were described by nonlinear regression. 3. Although the basal diets from the two studies were similar in ingredient composition, efficiencies of P utilisation (P accretion/P intake × 100) for the unsupplemented basal diets were 39% in Study 1 and 30% in Study 2. Phytase supplementation significantly improved P utilisation up to levels of about 55% in both studies. A plateau in P utilisation with an increase in phytase supplementation was achieved in Study 2, but not in Study 1. The enzyme was more efficient in Study 2 than in Study 1 at low rates of supplementation. Utilisation of calcium (Ca) was significantly improved by phytase supplementation. Accretions of P and Ca increased at a constant ratio. 4. In a 5-week growth study, diets with an intentionally marginal P level were used. Diets were fed either unsupplemented or supplemented with 1000 or 10 000 U/kg of phytase. Eight pens of 10 sex-separated ducks each (4 pens per sex) were allocated to each dietary treatment. 5. Phytase significantly improved the growth of ducks of both sexes between d 1 and 21, but not between d 22 and 35. Feed conversion rate was not affected by treatment. Blood serum phosphate concentrations, but not calcium, were significantly increased by phytase supplementation. Blood concentrations of creatinine, aspartate aminotransferase and lactate dehydrogenase remained unaffected while alanine aminotransferase was significantly reduced by phytase supplementation. 6. It was concluded that the efficacy of a microbial phytase varies even under similar experimental conditions. Differences in intrinsic phytase activity of maize/soybean meal-based diets may be responsible for this. The 6-phytase used has the potential to improve the utilisation of plant P in duck feeding. A plateau in response was reached above 1500 U/kg.