Characterization of a thermostable phytase from Bacillus licheniformis WHU and further stabilization of the enzyme through disulfide bond engineering

Phytases are important industrial enzymes widely used as feed additives to hydrolyze phytate and release inorganic phosphate. In this study, a phytase gene PhyBL isolated from Bacillus licheniformis WHU was cloned and expressed in Escherichia coli. PhyBL showed the highest activity at pH 7.0 and retained more than 40 % of its activity at a wide temperature range from 35 to 65 °C. Ca²⁺ significantly affected the stability and activity of the enzyme. We further improved the stability of PhyBL through extensively disulfide engineering. After constructing and screening a series of variants, an enhanced stable G197C/A358C variant was obtained. The G197C/A358C variant had a half-life at 60℃ roughly 3.8-fold longer than the wild type. In addition, the G197C/A358C variant also showed enhanced proteolytic resistance to pepsin and trypsin. The potential mechanism underlying these improvements was investigated by molecular dynamics analysis. Our results suggest that the G197C/A358C variant may have potential application as an additive enzyme in aquaculture feed.

A multistrategy approach for improving the expression of E. coli phytase in Pichia pastoris

Phytase is an additive in animal feed that degrades phytic acid in plant material, reducing feeding costs, and pollution from fecal phosphorus excretion. A multistrategy approach was adopted to improve the expression of E. coli phytase in Pichia pastoris. We determined that the most suitable signal peptide for phytase secretion was an α-factor secretion signal with an initial enzyme activity of 153.51 U/mL. Increasing the copy number of this gene to four increased phytase enzyme activity by 234.35%. PDI overexpression and Pep4 gene knockout increased extracellular phytase production by 35.33% and 26.64%, respectively. By combining favorable factors affecting phytase expression and secretion, the enzyme activity of the phytase-engineered strain was amplified 384.60% compared with that of the original strain. We also evaluated the potential for the industrial production of the engineered strain using a 50-L fed-batch fermenter and achieved a total activity of 30,246 U/mL after 180 h of fermentation.

Physiological Characteristics, Phytase Activity, and Mineral Bioavailability of a Low-Phytate Soybean Line during Germination

Phytate is a storage form of phosphorus (P) in seeds and, when degraded, plays a vital role in seed germination. Low phytate content in grain seeds inhibits germination and seedling growth. Here, Low-phytate (LP) and normal-phytate (NP) soybean lines were grown in vermiculite to determine whether germination was affected by low phytate content. Growth, phytase activity, mineral concentration, and mineral extractability from the seedlings of NP and LP soybean lines were evaluated. Seedling growth did not differ significantly between NP and LP lines. Phytase and specific phytase activities at 11 days to 17 days after sowing were 1.3 to 2.6 folds greater in the NP line than in the LP line. The LP line hydrolyzed all the phytate 2 days earlier than the NP line. The concentration and extractability of minerals changed over time during germination, and the LP line had higher molar ratios of phytic acid to Ca, Mg, and K than the NP line. These results suggest that germination and growth of the seedlings are not affected by low phytate levels in seeds. We suggest that the LP line benefits from higher bioavailability of P and macro-minerals unlike the NP line.

Over-processed meat and bone meal and phytase effects on broilers challenged with subclinical necrotic enteritis: Part 1. Performance, intestinal lesions and pH, bacterial counts and apparent ileal digestibility

This feeding study investigated the hypothesis that over-processing of meat and bone meal (MBM) would impair the performance, gut health and ileal digestibility of nutrients in birds challenged with necrotic enteritis (NE). The effect of phytase (500 vs. 5,000 FTU/kg) was also examined using manufacturers recommended matrix values for 500 FTU for both levels. Ross 308 male broilers (n = 768) were assigned to 8 diets, with 6 replicate pens per diet and 16 birds per replicate pen using a randomized design with a factorial arrangement of treatments. Factors were NE challenge (no or yes), MBM (as received or over-processed), and phytase level (500 or 5,000 FTU/kg). Half of the birds were challenged with 5,000 oocysts of field strains of Eimeria acervulina and Eimeria brunetti, and 2,500 oocysts of Eimeria maxima on d 9 and 108 CFU/mL of Clostridium perfringens strain EHE-NE18 on d 14 and 15 post-hatch. Challenge × MBM interactions were detected for weight gain (WG), feed conversion ratio (FCR) and feed intake (FI) at d 14, 21 and 28, showing that challenged birds fed over-processed MBM had decreased WG (P < 0.05) and FI (P < 0.05) at d 14, increased FCR (P < 0.05) at d 21 and decreased WG (P < 0.05) and FI (P > 0.05) at d 28. Birds fed low phytase had increased livability (P < 0.05) at d 42. The challenge increased the prevalence and severity of NE induced lesions in the jejunum (P < 0.05) and ileum (P < 0.05). The birds fed over-processed MBM had decreased pH in the jejunum (P < 0.05) and ileum (P < 0.05) at d 16. High phytase increased apparent ileal digestibility (AID) of Ca (P < 0.05) and P (P < 0.05), and over-processed MBM increased AID of carbon (C; P < 0.05) and Ca (P < 0.05) at d 29. The challenge increased the caecal counts of Lactobacillus spp. (P < 0.05) and C. perfringens (P < 0.05) at d 16. The results indicated that supplementation of diets with high phytase reduces the negative impact on performance from over-processed MBM during NE as a result of increased nutrient digestibility.

Safety evaluation of a novel variant of consensus bacterial phytase

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90-day oral and genetic toxicology studies were conducted on a next generation bacterial biosynthetic 6-phytase as an animal feed additive.

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No test article-related adverse effects were observed and a NOAEL was established as 1000 mg Total Organic Solids/kg bw/day.

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A margin of safety value of 1613 was calculated based on the NOAEL and an estimate of broiler feed consumption.

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Data support the safety of PhyG as an animal feed additive.

A 90-day subchronic oral toxicity study was conducted to evaluate the safety of a consensus bacterial phytase variant 6-phytase (PhyG) for use as an animal feed additive. This phytase is produced by fermentation with a fungal (Trichoderma reesei) production strain expressing a biosynthetic variant of a consensus bacterial phytase gene assembled via ancestral reconstruction with sequence bias for the phytase from Buttiauxella sp. Rats were administered PhyG daily via oral gavage at dose-levels of 0 (distilled water), 250, 500 or 1000 mg total organic solids (TOS)/kg bodyweight (bw)/day (equivalent to 0, 112,500, 225,000 and 450,000 phytase units (FTU)/kg bw/day, respectively). No test article-related adverse effects were observed. A no-observed-adverse-effect level (NOAEL) for PhyG was established as 1000 mg TOS/kg bw/day, the highest test concentration. Based on this NOAEL and an estimate of broiler consumption determined from the proposed inclusion of the phytase in feed at the maximum recommended level (4000 FTU/kg), a margin of safety value of 1613 was calculated. Results of in vitro genotoxicity testing and in silico protein toxin evaluation further confirmed PhyG to be non-genotoxic and not likely to be a protein toxin upon consumption. These data support the safety of PhyG as an animal feed additive.

Recovery and purification of Aspergillus niger phytase from crude extract using AOT / isooctane reversed micelles

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The application of the reverse micelles resulted in purification of A. niger phytase.

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It was possible purify phytase from A. niger by reversed micelles in short period time.

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Reversed micelles proved to be a viable alternative for phytase purification.

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Phytase remained active after extraction using AOT/isooctane reversed micelles.

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The phytase purity and activity were confirmed by SDS-PAGE and zymogram analyzes.

This work describes the successful extraction of Aspergillus niger phytase from a crude extract (CE) obtained from solid-state fermentation by reversed micelle system using anionic surfactant sodium bis (2-ethylhexyl) sulfosuccinate (AOT) in isooctane achieved in two simple steps: forward and backward extractions. The effects of potassium chloride (KCl) concentration, pH of the aqueous solution, and AOT concentration that affect the system were examined. The best result for the forward extraction was obtained with the CE solution at pH 4.0, 50 mM KCl, and 100 mM AOT, while for the backward extraction the best result was achieved with a stripping aqueous solution at pH 5.5 containing 200 mM KCl, achieving a purification factor of 4.03, 1.15 times higher than that reported for the conventional purification process. Phytase purity was demonstrated by SDS-PAGE (89 kDa) and its activity by zymogram, confirming the efficiency of the process with low time consumption (∼40 min).

Production and characterization of volatile compounds and phytase from potentially probiotic yeasts isolated from traditional fermented cereal foods in Nigeria

BACKGROUND

Probiotic strains are incorporated into food substrates to contribute to fermentation process. The technological suitability of such strains to improve the flavor and nutritional value of fermented food is strain-specific. Potentially probiotic yeasts isolated from Nigerian traditional fermented foods were assessed for production of volatile compounds by gas chromatography-mass spectrophotometry. Phytases were characterized for activity and stability at different pH (3-8) and temperatures (25-50 °C).

RESULTS

A total of 45 volatiles compounds were identified from intracellular cell-free extracts of Pichia kluyveri LKC17, Issatchenkia orientalis OSL11, P. kudriavzevii OG32, P. kudriavzevii ROM11, and Candida tropicalis BOM21. They include alcohols (14), carbonyls (13), esters (10), and organic acids (8). Phenylethyl alcohol was the highest higher-alcohol in Issatchenkia orientalis OSL11 (27.51 %). The largest proportion of esters was detected in P. kudriavzevii OG32 (17.38 %). Pichia kudriavzevii OG32 and C. tropicalis BOM21 showed vigorous gowth in minimal medium supplemented with sodium phytate (2 g L-1). Extracellular phytases from P. kudriavzevii OG32 and Candida tropicalis BOM2 showed optimal activiy at pH 4.6 (104.28 U) and pH 3.6 (81.43 U) respectively.

CONCLUSIONS

Results obtained revealed species- and strain-specific potentials of the yeast strains to improve flavor and mineral bioavailability of fermented food products. Therefore, the application of these yeasts as starter cultures during food fermentation process is a very promising method to enhance the flavor profile and enhance mineral bioavailability in indigenous cereal-based fermented food products.

Engineering and optimization of phosphate-responsive phytase expression in Pichia pastoris yeast for phytate hydrolysis

Phytate is the major storage form of phosphorus in plants. It is present in cereals and raw materials of vegetable origin used in animal and human diets. However, non-ruminant animals have little phytase activity in their guts and, therefore, cannot digest phytate. As a result, almost all dietary phytate is discharged into the environment, causing phosphorus pollution. Phytate is also considered as an "antinutrient" for its ability to form insoluble and stable complexes with metal ions, thus reducing dietary absorption of essential minerals. It is a dire need to develop sustainable approaches for environmentally-friendly utilization for this valuable and abundant natural resource. To this end, we engineered Pichia pastoris to express and secrete phytase in a "made-to-order" fashion in response to external level of inorganic phosphate (Pi). Responsiveness to external Pi level was achieved by generating a Pi-responsive promoter library using directed evolution. The resultant yeast strains were proven to liberate Pi from wheat-based meal in a simulated in vitro digestion model. These yeast-based whole cell biocatalysts may serve as platform hosts with potential applications in food processing industry and animal waste treatment.

Production performances and antioxidant activities of laying hens fed Aspergillus oryzae and phytase co-fermented wheat bran

OBJECTIVE

Wheat bran (WB) was co-fermented with Aspergillus oryzae and phytase (Phy) to determine whether co-fermentation improve WB phosphorus and fiber utilization in Isa-brown layers.

METHODS

A total of 112 Isa brown layer were randomly divided into 7 treatments with 8 replicates per a treatment and 2 hens per a replicate. The treatments included basal diet (control), basal diet supplemented with 250 unit/kg Phy (control+Phy), diet with 10% WB (10% WB), diet with 5% WB and 250 unit/kg Phy (5% WB+Phy) diet with 10% WB and 250 unit/kg Phy (10% WB+Phy), diet with 5% fermented WB supplemented with molasses and phy (PCFWH) and 125 unit/kg Phy (5% PCFWH), and diet with 10% PCFWH (10% PCFWH). The intestinal microbial population, intestinal morphology, serum antioxidant enzyme activities, and excreta phosphorus content were assessed.

RESULTS

In PCFWH, spore counts, protease activity, xylanase activity, and ferulic acid were 8.50 log/g dry matter (DM), 190 unit/g DM, 120 unit/g DM, and 127 μg/g, respectively. Xylobiose and xylotriose were released in PCFWH, while they were not detectable in WB. Antioxidant capacity was also enhanced in PCFWH compared to WB. The 10% WB+Phy and 10% PCFWH groups produced higher egg mass, but hens fed 5% WB+Phy had the lowest amount of feed intake. Eggs from 10% PCFWH had better eggshell weight, eggshell strength, and eggshell thickness. Birds fed with 10% PCFWH also had higher serum superoxide dismutase and catalase activities. Compare to control, 10% PCFWH significantly reduced excreta phosphorus content.

CONCLUSION

Diet inclusion of 10% PCFWH improved egg quality, antioxidant status, and excreta phosphorus content of laying hens.

Physiological and genetic characterization of indigenous Saccharomyces cerevisiae for potential use in productions of fermented maize-based-beverages

The Saccharomyces cerevisiae has been used for many years in the elaboration of food and beverage products, mainly associated with fermentation processes. The objective of this study was to characterize different indigenous S. cerevisiae strains and guide the notable strains for potential use in productions of fermented maize-based beverages. Initially, 81 strains isolated from different spontaneous food fermentations were evaluated. About 31% of strains showed phytase activity, an important characteristic for their application in cereals beverages production. All strains were able to grow in pH values 2.0, 3.0, and 5.0 and the presence of 5, 15, and 30% of glucose, but none could grow at 42 °C. Only 29.6% of the evaluated strains were able to efficiently grow in up to 1.0 mol L^-1 of NaCl. The Rep-PCR and RAPD-PCR tools showed that the strains were differently grouped by the two techniques, and the grouping was not completely correlated with isolation source. A total of 65 volatile compounds were identified from the maize beverage produced. The profiles of volatile compounds produced by the strains were strain specific. S. cerevisiae strains isolated from the same source showed different chemical and genetic profiles, emphasize the importance to characterize the performance of each strain when searching for starter culture to develop or improve fermented beverages.

A novel fungal beta-propeller phytase from nematophagous Arthrobotrys oligospora: characterization and potential application in phosphorus and mineral release for feed processing

Phytases are widely utilized in feed industry to increase the utilization of phosphorus, minerals, and amino acids for improvement of animal and human nutrition. At present, all known β-propeller phytases (BPP) have been generated from bacteria, particularly Bacillus. In this work we report for the first time a new fungal-derived BPP phytase. We identified a phytase highly differentially expressed only in the parasitic stage of a nematophagous fungus, Arhtrobotrys oliogospora, during the development of the 3D traps. We found that this phytase was homologous to the known bacterial BPP phytase, thus we referred the new phytase to Aophytase. The heterologous expression of codon-optimized Aophytase gene in Pichia pastoris was successfully investigated to yield recombinant Aophytase (r-Aophytase) with high specific enzyme activity of 74.71 U/mg, much higher than those of recombinant BPP phytases derived bacteria. The kinetic parameters of the r-Aophytase, the optimum pH and temperature, as well as the effects of surfactant, EDTA and different ions on its enzyme activity were further investigated. The potential utilization of r-Aophytase in feed processing was finally explored. We found that the optimal pH value was about 7.5, and the optimal temperature was 50 °C.; r-Aophytase significantly increased the release of inorganic phosphorus from soybean meal, and improved the release of soluble minerals from the durum wheat flour and finger millet flour. The findings indicate its potential utilization in the feed processing to ameliorate nutritional value of cereals and animal feed in the future.

Seedling growth, physiological characteristics, nitrogen fixation, and root and nodule phytase and phosphatase activity of a low-phytate soybean line

Understanding the influence of the valuable "low-phytate" trait on soybean seedling growth, physiology, and biochemistry will facilitate its future exploitation. The aim was to elucidate the physiological and biochemical characteristics of low-phytate (LP) soybean at the seedling stage. To this end, seed P and mineral content and seedling dry weight, carbon (C) and nitrogen (N) accumulation, nitrogen fixation, and root and nodule phytase and phosphatase activity levels were measured at 21 d after sowing LP and normal-phytate (NP) soybean lines. Seedling dry weight, and C and N accumulation were 31%, 38% and 54% higher, respectively, in the LP line than the NP line. The total and specific nitrogen fixation levels in the LP nodules were 46% and 78% higher, respectively, than those in the NP nodules. The phytase, phosphatase, and specific phytase levels were 1.4-folds, 1.3-folds, and 1.3-folds higher, respectively, in the LP roots than the NP roots. The phosphatase and specific phosphatase levels in LP nodules were 1.5-folds and 1.3-folds higher, respectively, than those in the NP nodules. The mineral levels were substantially higher in the LP seeds and seedings than in those of the NP line. The HCl extractabilities of P, S, Fe, Cu and Mn were higher in the LP seeds than the NP seeds. These results indicate that the LP line presented with superior seedling growth and nitrogen fixation relative to the NP line. The LP line had relatively higher root phytase and root and nodule phosphatase activity levels than the NP line and could, therefore, be better suited and more readily adapt to low P conditions.

Production of Phytase Enzyme by a Bioengineered Probiotic for Degrading of Phytate Phosphorus in the Digestive Tract of Poultry

Probiotics are beneficial microorganisms and have long been used in food production as well as health promotion products. Bioengineered probiotics are used to express and transfer native or recombinant molecules to the mucosal surface of the digestive tract to improve feed efficiency and promote health. Lactococcus lactis is a potential probiotic candidate to produce useful biological proteins. The aim of this investigation was to develop a recombinant Lactococcus lactis with the potential of producing phytase. To enhance the efficiency of expression and secretion of recombinant phytase, usp45 signal peptide was added to the expression vector containing phytase gene (appA2) derived from Escherichia coli. Sequencing of recombinant plasmid containing appA2 showed the correct construction of plasmid. Total length of the phytase insert was 1.25 kbp. A Blast search of the cloned fragment showed 99% similarity to the reported E. coli phytase sequence in the GenBank (accession number: AM946981.2). A plasmid containing usp45 and appA2 electrotransferred into Lactococcus lactis. Zymogram with polyacrylamide gel revealed that the protein extract from the supernatant and the cell pellet of recombinant bacteria had phytase activity. Enzyme activity of 4 U/ml was obtained in cell extracts, and supernatant maximal phytase activity was 19 U/ml. The recombinant L. lactis was supplemented in broiler chicken feed and showed the increase of apparent digestibility on phytate phosphorus in the digestive tract and it was same as performance of E. coli commercial phytase.

Dephytinizing and Probiotic Potentials of Saccharomyces cerevisiae (NCIM 3662) Strain for Amelioration of Nutritional Quality of Functional Foods

Increase of undigested complexes of phytic acid in food is gaining serious attention to overcome nutritional challenges due to chelation effects. We investigated soil-borne yeast phytase from Saccharomyces cerevisiae (NCIM 3662) for dephytinization of foods, probiotic properties, and process development. The strain produced 45 IU/DCG by cell-bound phytase in an unoptimized medium was increased fourfold (164 IU/DCG) in 12 h using statistical media optimization. The process was scaled-up up to 10-L fermenter scale with increased phytase productivity of 6.4 IU/DCG/h as compared to the lab scale. The strain displayed probiotic characteristics like tolerance to artificial gastric acid conditions, hydrophobicity, autoaggregation, coaggregation, and bile salt hydrolase (BSH) activity. Further, it could dephytinize (removal of phytic acid; an anti-nutritional factor) functional foods like ragi (finger millet) flour, soya flour, chickpea flour, and poultry animal feed. A combination of cell-bound dephytinizing phytase and nutrition-ameliorating probiotic traits of S. cerevisiae (NCIM 3662) presents profound applications in food technology sector.

Finding of phytase: Understanding growth promotion mechanism of phytic acid to freshwater microalga Euglena gracilis

To better understand the promotion effect of phytic acid and its uptake mechanism in freshwater microalga Euglena gracilis, cell growth, photosynthetic pigment content and cell morphology of E. gracilis were evaluated under four conditions: phosphorus deficient group (CMP-), single phosphate treatment group (CMP+), single phytic acid treatment group (CMPA-), and phosphate-phytic acid mixed treatment group (CMPA+). The results showed that phytic acid could serve as the sole phosphorus source for the growth of E. gracilis, and phytase which catalyzes the hydrolysis of phytic acid was discovered for the first time in E. gracilis. Fourier transform infrared spectroscopy combined with multivariate analysis showed the good recognition of metabolites from different culture conditions especially focusing on relative carbohydrate or lipid contents. Phytic acid derived from agro-wastes is a cheap growth promoter for E. gracilis, and this E. gracilis with high nutritional value is applicable to animal feed while minimizing environmental impact.

Characteristics of an Acidic Phytase from Aspergillus aculeatus APF1 for Dephytinization of Biofortified Wheat Genotypes

Phytases are the special class of enzymes which have excellent application potential for enhancing the quality of food by decreasing its inherent anti-nutrient components. In current study, a protease-resistant, acidic phytase from Aspergillus aculeatus APF1 was partially purified by ammonium sulfate fractionation followed by chromatography techniques. The molecular weight of partially purified phytase was in range of 25-35 kDa. The purified APF1 phytase was biochemically characterized and found catalytically active at pH 3.0 and 50 °C. The K_m and V_max values of APF1 phytase for calcium phytate were 3.21 mM and 3.78 U/mg protein, respectively. Variable activity was observed with metal ions and among inhibitors, chaotropic agents and organic solvents; phenyl glyoxal, potassium iodide, and butanol inhibited enzyme activity, respectively, while the enzyme activity was not majorly influenced by EDTA, urea, ethanol, and hexane. APF1 phytase treatment was found effective in dephytinization of flour biofortified wheat genotypes. Maximum decrease in phytic acid content was noticed in genotype MB-16-1-4 (89.98%) followed by PRH₃-30-3 (82.32%) and PRH₃-43-1 (81.47%). Overall, the study revealed that phytase from Aspergillus aculeatus APF1 could be effectively used in food and feed processing industry for enhancing nutritional value of food.

Calcium exerts a strong influence upon phosphohydrolase gene abundance and phylogenetic diversity in soil

The mechanisms by which microbial communities maintain functions within the context of changing environments are key to a wide variety of environmental processes. In soil, these mechanisms support fertility. Genes associated with hydrolysis of organic phosphoesters represent an interesting set of genes with which to study maintenance of function in microbiomes. Here, we shown that the richness of ecotypes for each gene varies considerably in response to application of manure and various inorganic fertilizer combinations. We show, at unprecedented phylogenetic resolution, that phylogenetic diversity of phosphohydrolase genes are more responsive to soil management and edaphic factors than the taxonomic biomarker 16S rRNA gene. Available phosphorus - assessed by measuring Olsen-P - exerted some influence on alkaline phosphatase distribution: however, consistent and significant differences were observed in gene abundance between treatments that were inconsistent with bioavailable orthophosphate being the dominant factor determining gene abundance. Instead, we observed gene niche separation which was most strongly associated with soil exchangeable calcium. Our study suggests that the bioavailability of enzyme cofactors (exchangeable calcium in the case of phoD, phoX and βPPhy studied here) influence the abundance of genes in soil microbial communities; in the absence of cofactors, genes coding for alternative enzyme families that do not require the limiting cofactor (for example, non-specific acid phosphatases which require vanadate) become more abundant.

Effect of phytase on phosphorous balance in 20-kg barrows fed low or adequate phosphorous diets

The effects of phytase on phosphorus (P) digestibility are well established. However, there are few studies that report P balance, particularly when phytase is used in diets that have adequate or deficient P. The main objective of the study was to determine the effect of dietary P levels and exogenous phytase on P balance in growing pigs. The first part of the experiment was a 14-d metabolism study conducted with 80 barrows (initial body weight 18.5 ± 0.5 kg) with a 2 × 5 factorial arrangement of treatments and main effects of available P (0.13% available P, low P [Low-P] diet; 0.35% available P, adequate P [Adeq-P] diet) and phytase (0, 250, 500, 2,500, and 12,500 U/kg). A portion of the pigs (n = 24) fed the Low-P diet, with 0, 500, 2,500, 12,500 U/kg phytase, and those fed the Adeq-P diet, with 0 and 12,500 U/kg phytase, remained on test diets for another 4 d, and tissues were collected for determination of bone characteristics and tissue P concentration. There was a P × phytase interaction for P retention that was accounted for by a lack of response to phytase in pigs fed the Adeq-P diet. Retention of P was greater with incremental levels of phytase in pigs fed Low-P diets as compared to those fed Adeq-P diets (P level × phytase, P < 0.01), but calcium (Ca) retention was greater in pigs fed Adeq-P diets (P level × phytase P < 0.01). Apparent total tract digestibility (ATTD) of P was improved by phytase (P < 0.001) and was greater in pigs fed Adeq-P diets as compared to those fed Low-P diets (P = 0.006). Metatarsal bone ash (quadratic, P = 0.01) and strength (linear, P = 0.03) was increased by phytase addition to the Low-P diets. There were no phytase or dietary P effects on P concentrations of the heart, kidney, liver, muscle, and spleen. These results suggest that as compared to the effects in an Adeq-P diet, adding phytase to a Low-P diet was more effective at reducing the P and Ca excretion and restoring average daily gain (ADG). The P released by phytase is absorbed and contributes to improved bone growth, greater rates of tissue accretion, and increased body weight, but does not change tissue P concentrations. There is, however, a threshold for P retention, beyond which it is excreted in the urine.

The influence of phytase, pre-pellet cracked maize and dietary crude protein level on broiler performance via response surface methodology

Background

The reduction of crude protein levels in diets for broiler chickens may generate economic, environmental and flock welfare and health benefits; however, performance is usually compromised. Whole grain feeding and phytase may improve the utilization of reduced crude protein diets.

Results

The effects of pre-pellet cracked maize (0, 15% and 30%) and phytase (0, 750 and 1500 FTU/kg) in iso-energetic maize-soy diets with three levels of crude protein (22%, 19.5% and 17%) were evaluated via a Box-Behnken response surface design. Each of 13 dietary treatments were offered to 6 replicate cages (6 birds/cage) of male Ross 308 broiler chicks from 7 to 28 d post-hatch. Model prediction and response surface plots were generated from experimental data via polynomial regression in R and only significant coefficients were included and discussed in the predicted models. Weight gain, feed intake and FCR were all influenced by pre-pellet cracked maize, phytase and crude protein level, where crude protein level had the greatest influence. Consequently, the reduction from 22% to 17% dietary crude protein in non-supplemented diets reduced weight gain, feed intake, relative gizzard weight, relative gizzard content and relative pancreas weight but improved FCR. However, the inclusion of 30% cracked maize to 17% crude protein diets restored gizzard weight and 1500 FTU phytase inclusion to 17% crude protein diets increased relative gizzard contents and pancreas weights. Cracked maize and phytase inclusion in tandem to 17% crude protein diets increased weight gain, feed intake and FCR; however, this FCR was still more efficient than broilers offered the non-supplemented 22% crude protein diet. Broilers offered the pre-pellet cracked maize and phytase inclusions reduced AME in 22% crude protein diets but improved AME by 2.92 MJ (14.16 versus 11.24 MJ; P < 0.001) in diets containing 17% crude protein. Ileal N digestibility was greater in broilers offered diets with 17% crude protein than those offered the 22% crude protein diet; irrespective of phytase and pre-pellet cracked maize.

Conclusion

Pre-pellet cracked maize and phytase inclusions will improve the performance of broilers offered reduced crude protein diets.

An in vitro chicken gut model for the assessment of phytase producing bacteria

An in vitro simulated chicken gut model was proposed for studying the phytase activity of selected bacteria such as Streptococcus thermophilus, Sporosarcina pasteurii, Sporosarcina globispora, and Sporosarcina psychrophila using known probiotic bacterium, Lactobacillus helveticus as a control. The selected bacteria were viable in the intestinal lumen and produced extracellular phytase at optimal phytate concentration of 6.25 mM when compared to 3.125 mM and 12.5 mM. These bacteria demonstrated significantly higher (p < 0.05) phosphate liberation (up to 387 µM) due to better phytase activity in the production medium, when compared to the growth medium (339 µM). The phytase activity showed a steady increase in phosphate liberation up to 150 min after which it became constant. This trend is observed for the selected bacteria at pH 5, 6 and 7. However, the liberation of phosphates showed no significant difference (p > 0.05) at the tested pH. Among the analyzed bacteria, the members of the genus Sporosarcina showed better phytate degradation when compared to S. thermophilus. The proposed model can be extended to analyze any extracellular enzymes produced by gut microbes.

Comparing methods of genetic manipulation in Bacillus subtilis for expression of recombinant enzyme: Replicative or integrative (CRISPR-Cas9) plasmid?

The present study evaluated the stability of Bacillus subtilis strains transformed with a replicative or integrative plasmid (via CRISPR-Cas9) to express a recombinant phytase. Both transformation methods did not affect the growth of B. subtilis, but the stability of the construct and the enzymatic activity was reduced in the strain transformed with the replicative plasmid.

Impact of coccidiostat and phytase supplementation on gut microbiota composition and phytate degradation in broiler chickens

Background

There is good evidence for a substantial endogenous phytase activity originating from the epithelial tissue or the microbiota resident in the digestive tract of broiler chickens. However, ionophore coccidiostats, which are frequently used as feed additives in broiler diets to prevent coccidiosis, might affect the bacterial composition and the abundance of phytase producers in the gastrointestinal tract. The aim of the present study was to investigate whether supplementation of a frequently used mixture of the coccidiostats Narasin and Nicarbazin alone or together with a phytase affects microbiota composition of the digestive tract of broiler chickens, characteristics of phytate breakdown in crop and terminal ileum, and precaecal phosphorus and crude protein digestibility.

Results

Large differences in the microbial composition and diversity were detected between the treatments with and without coccidiostat supplementation. Disappearance of myo-inositol 1,2,3,4,5,6-hexakis(dihydrogen phosphate) (InsP₆) in the digestive tract, precaecal P digestibility, inorganic P in blood serum, and the concentration of inositol phosphate isomers in the crop and ileum digesta were significantly affected by phytase supplementation, but not by coccidiostat supplementation. Crude protein digestibility was increased by coccidiostat supplementation when more phosphate was available. Neither microbial abundance and diversity nor any other trait measured at the end of the experiment was affected by coccidiostat when it was only supplemented from day 1 to 10 of age.

Conclusions

The coccidiostats used herein had large effects on overall microbiota composition of the digestive tract. The coccidiostats did not seem to affect endogenous or exogenous phytase activity up to the terminal ileum of broiler chickens. The effects of phytase on growth, phosphorus digestibility, and myo-inositol release were not altered by the presence of the coccidiostats. The effects of phytase and coccidiostats on nutrient digestibility can be of significant relevance for phosphorus and protein-reduced feeding concepts if confirmed in further experiments.

Electronic supplementary material

The online version of this article (10.1186/s42523-019-0006-2) contains supplementary material, which is available to authorized users.

Use of Plackett-Burman design for enhanced phytase production by Williopsis saturnus NCIM 3298 for applications in animal feed and ethanol production

Distiller-dried grain solid (DDGS), a co-product of alcohol production, contains cereal grain residues, proteins, and yeast metabolites, which make it suitable in poultry feeding. However, high phytate content of DDGS limits its applicability in poultry feed. In this study, Plackett-Burman design was used to improve cell-bound phytase production by Williopsis saturnus NCIM 3298, and we achieved an enzyme activity of 269 IU/g of dry-wet biomass. The effect of this enhanced phytase-displaying yeast strain on hydrolysis of corn phytate and subsequently on ethanol production and DDGS quality was then investigated. Results of saccharification in the presence of phytase showed that reducing sugar content of liquefied mash increased by 11%, which subsequently improved the ethanol production by 18% (w/v) (p < 0.01) compared with the control. Notably, phytase treatment decreased the phytate content of corn by 70% (p < 0.01) compared with the control, thereby improving the availability of free phosphate in fermentation broth and DDGS. Thus, the results obtained suggest that the addition of W. saturnus NCIM 3298 strain has the potential of providing a new source of phytase that would be useful in the feed and ethanol industries.

Genetic transformation of tropical maize (Zea mays L.) inbred line with a phytase gene from Aspergillus niger

A full-length cDNA of phyA gene of Aspergillus niger, encoding phytase enzyme, was cloned and expressed in E. coli BL21 cells and assayed for its activity. The phyA cDNA consisted of 1404 bp, which encoded 467 amino acid residues. The phytase activity of purified phytase was 826.33 U/mL. The phyA gene under the control of endosperm-specific promoters was transformed into an Indian maize inbred line, UMI29, using particle bombardment-mediated transformation method to generate transgenic maize plants over-expressing phytase in seeds. PCR and GUS analyses demonstrated the presence of transgenes in T₀ transgenic plants and their stable inheritance in the T₁ progenies. Three transgenic events expressing detectable level of A. niger phytase were characterized by western blot analysis. Phytase activity of 463.158 U/kg of seed was observed in one of the events, JB-UMI29-Z17/2. The phytase activity of transgenic maize seeds was 5.5- to 7-fold higher than the wild-type UMI29 seeds and, consequently, the seeds had 0.6- to 5-fold higher inorganic phosphorus content.

Phytase-Fe3O4 nanoparticles-loaded microcosms of silica for catalytic remediation of phytate-phosphorous from eutrophic water bodies

Agriculture P management practices elevate the level of inorganic phosphates in soil that results in phosphorous (P) seepage into water-bodies. This is one of the key factors that have accelerated the menace of eutrophication. Phytic acid (phytate)-P-rich plant metabolite is infamous for its anti-nutrient activity and regularly oozing in to environment though discharge of mono-gastric animals. That has amplified the magnitudes of eutrophication. In this work, for catalysis of phytate-P, the metal-organic framework fabricated towards metal oxides (Fe₃O₄) and phytase in highly ordered microcosms of silica was employed. The synthesized framework was characterized through transmission electron microscopy (TEM) and nitrogen isotherm analysis. Average pore diameter of synthesized bisect oval shaped structures was measured around ≈200 nm. Herein, phytase and Fe₃O₄ nanoparticles were loaded to the cavities of microcosms through glutaraldehyde-mediated crosslinking. Whereas Fe₃O₄ nanoparticles act as nano-absorbents that adsorb P liberated from phytase-mediated catalysis of phytate. Kinetic analysis of free and loaded phytase has shown relatively small reduction in catalytic efficiency. These loaded microcosms have removed 60-80% of phytate-phosphate. The optimized process has reduced the growth of photoautotrophs by 50%. Additionally the magnet-assisted separation of loaded microcosms eased the reapplication of loaded microcosms tested for six independent instances. The primary studies conducted to evaluate the geno-toxicity of loaded microcosms have not shown any harmful effect on the process like cell division and seed germination. The efficacy of this method has evaluated towards on-field testing in Changa (Gujarat, India) lake.