Thermostable phytase in feed and fuel industries

Phytase with wide ranging biochemical properties has long been utilized in a multitude of industries, even so, thermostability plays a crucial factor in choosing the right phytase in a few of the sectors. Mesophilic phytases are not considered to be a viable option in the feed industry owing to its limited stability in the required feed processing temperature. In the recent past, inclusion of thermostable phytase in fuel ethanol production from starch based raw material has been demonstrated with economic benefits. Therefore, considerable emphasis has been placed on using complementary approaches such as mining of extremophilic microbial wealth, encapsulation and using enzyme engineering for obtaining stable phytase variants. This article means to give an insight on role of thermostable phytases in feed and fuel industries and methods for its development, highlighting molecular determinants of thermostability.

Influence of phytase enzyme on ruminal biogas production and fermentative digestion towards reducing environmental contamination

Environmental impact of livestock production has received a considerable public scrutiny because of the adverse effects of nutrient run-offs, primarily N and P, from agricultural land harboring intensive energy livestock operations. Hence, this study was designed to determine the efficacy of dietary phytase supplementation on fermentation of a sorghum grain-based total mixed ration (TMR) using a ruminal in vitro digestion approach. Phytase was supplemented at three doses: 0 (control), 540 (P540), and 720 (P720) g/t dry matter, equivalent to 0, 2.7 × 10⁶, and 3.6 × 10⁶ CFU/t DM, respectively. Compared to P720 and the control, gas production was higher for P540 after 12 h (P = 0.02) and 24 h (P = 0.03) of fermentation suggesting a higher microbial activity in response to phytase supplementation at lower phytase levels. Correspondingly, dry matter degradability was found to have improved in P540 and P720 compared to the control by 13 and 11% after 24 h of incubation (P = 0.05). For ammonia nitrogen (NH₃-N), a tendency towards lower values was only observed for P540 at 24 h of fermentation (P = 0.07), while minimal treatment effects were observed at other fermentation times. The concentrations of total volatile fatty acids (VFA) were higher (P < 0.05) after 48 h of fermentation for P540 and P720 compared to the control (P = 0.03) by 10% and 14%, respectively. Ruminal acetate tended towards higher values in the presence of phytase after 12 h of fermentation (P = 0.10), but towards lower values after 24 h of fermentation (P = 0.02), irrespective of the phytase dose applied. A trend towards lower ruminal propionate levels was observed in the presence of phytase after 6 h (P = 0.10) and 12 h (P = 0.06) of fermentation, while no effects were found at other fermentation times. In conclusion, phytase supplementation has the potential to improve metabolic energy activity of rumen microorganisms and the use of feed constituents. Thus, phytase supplementation could help to reduce environmental contamination in areas of ruminant production.

Response of broiler chickens to diets containing different levels of sodium with or without microbial phytase supplementation

Phytate induced excessive mineral excretion through poultry litter leads to poor performance and environmental pollution. Exogenous microbial phytase supplementation to poultry diets reduce the environmental excretion of nutrient and improve bird’s performance. However, excessive dietary sodium (Na) level may hinder the phytase-mediated phytate hydrolysis and negate the beneficial effects of phytase. Therefore, this experiment was conducted to investigate the effects of different concentration dietary Na on phytase activity and subsequent impact on broiler performance, bone mineralisation and nutrient utilisation. In this study, six experimental diets, consisting of three different levels of Na (1.5, 2.5, or 3.5 g/kg) and two levels of microbial phytase (0 or 500 U/kg) were formulated by using 3 × 2 factorial design. The six experimental diets were offered to 360 day-old Ross 306 male chicks for 35 days, where, each experimental diet consisted of 6 replicates groups with 10 birds. Along with growth performance, nutrient utilization, intestinal enzyme activity, dry matter (DM) content of litter and mineral status in bone were analysed. Dietary Na and phytase had no effect on bode weight gain and feed intake. Birds on the low Na diet showed higher (p < 0.05) feed conversion ratio (FCR) than the mid-Na diets. High dietary Na adversely affected (p < 0.001) excreta DM content. Phytase supplementation to the high-Na diet increased (p < 0.01) the litter ammonia content. High dietary Na with phytase supplementation improved (Na × phytase, p < 0.05) the AME value and ileal digestibility of Ca and Mg. The total tract retention of Ca, P, and Mg was reduced with high Na diet, which was counteracted by phytase supplementation (Na × phytase, p < 0.001). The diets containing mid-level of Na improved (p < 0.001) the function of Na-K-ATPase and Mg-ATPase in the jejunum. The overall results indicate that high dietary Na did not affect phytase activity but influenced the nutrient utilization of birds, which was not reflected in bird overall performance.

Evolution of E. coli Phytase for Increased Thermostability Guided by Rational Parameters

Phytases are enzymes that can hydrolyze phytate and its salts into inositol and phosphoric acid, and have been utilized to increase the availability of nutrients in animal feed and mitigate environmental pollution. However, the enzymes’low thermostability has limited their application during the feed palletization process. In this study, a combination of B-value calculation and protein surface engineering was applied to rationally evolve the heat stability of Escherichia coli phytase. After systematic alignment and mining for homologs of the original phytase from the histidine acid phosphatase family, the two models 1DKL and 1DKQ were chosen and used to identify the B-values and spatial distribution of key amino acid residues. Consequently, thirteen potential amino acid mutation sites were obtained and categorized into six domains to construct mutant libraries. After five rounds of iterative mutation screening, the thermophilic phytase mutant P56214 was finally yielded. Compared with the wild-type, the residual enzyme activity of the mutant increased from 20% to 75% after incubation at 90°C for 5 min. Compared with traditional methods, the rational engineering approach used in this study reduces the screening workload and provides a reference for future applications of phytases as green catalysts.

Sampling duration and freezing temperature influence the analysed gastric inositol phosphate composition of pigs fed diets with different levels of phytase

This experiment was conducted to determine the effects of time and freezing temperature during sampling on gastric phytate (myo-inositol [MYO] hexakisphosphate [InsP₆]), lower inositol phosphates (InsP_2–5) and MYO concentrations in pigs fed diets containing different levels of phytase. Forty pigs were fed 1 of 4 wheat-barley diets on an ad libitum basis for 28 d. The diets comprised a nutritionally adequate positive control (PC), a similar diet but with Ca and P reduced by 1.6 and 1.24 g/kg, respectively (NC), and the NC supplemented with 500 (NC + 500) or 2,000 (NC + 2000) FTU phytase/kg. At the end of the experiment, chyme were collected from the stomach, thoroughly mixed and 2 subsamples (30 mL) were frozen immediately: one snap-frozen at −79 °C and the other at −20 °C. The remaining chyme were left to sit at room temperature (20 °C) and further subsamples were collected and frozen as above at 5, 10 and 15 min from the point of mixing. There were linear reductions in gastric InsP₆ concentration over time during sampling (P < 0.001), irrespective of diet or freezing temperature. Moreover, InsP₆ concentration was influenced by a diet × freezing temperature interaction (P < 0.05), with less InsP₆ measured in chyme frozen at −20 °C than at −79 °C; however, this difference was greater in the control diets than the phytase supplemented diets. Freezing chyme at −79 °C recovered more ∑InsP_2–5 + MYO than freezing at −20 °C in pigs fed phytase supplemented diets; however, this difference was not apparent in the diets without phytase (diet × freezing temperature, P < 0.01). It can be concluded that significant phytate hydrolysis occurs in the gastric chyme of pigs during sampling and processing, irrespective of supplementary phytase activity. Therefore, to minimise post-slaughter phytate degradation and changes in the gastric inositol phosphate profile, chyme should be snap-frozen immediately after collection.

Partial purification and characterization of phytase from Aspergillus foetidus MTCC 11682

Phytase is a phosphatase enzyme widely used as feed additive to release inorganic phosphorus from plant phytate and enhance its uptake in monogastric animals. Although engineered fungal phytases are used most, a natural enzyme gives opportunity to understand novel properties, if any. In the current study, a novel fungal strain, Aspergillus foetidus MTCC 11682 was immobilized on poly urethane cubes and used for phytase production, purification and molecular characterization. Phytase produced by this method was partially purified by ammonium sulphate precipitation and Sephacryl S-200HR gel filtration to 23.4-fold (compared to crude extract) with recovery of 13% protein. Electrophoresis analysis revealed that phytase has molecular weight of 90.5 kDa on non-reducing and 129.6 kDa on reducing SDS-PAGE. The purified phytase exhibited a wider pH and temperature stability. Analysis of the cloned sequence showed that the gene has 1176 bp that encodes for a peptide of 391 amino acids of the core catalytic region. It was also found that phytase from A. foetidus has a sequence identity of 99% with the phytase gene of other Aspergillus species at nucleotide level and 100% at protein level in A. niger, A. awamori, A. oryzae. In silico analysis of sequence identified the presence of two consecutive and one non-consecutive intra chain disulfide bonds in the phytase. This probably contributed to the differential migration of phytase on reducing and non-reducing SDS-PAGE. There are predicted 11 O-glycosylation sites and 8 N-glycosylation sites, possibly contributed to an enhanced stability of enzyme produced by this organism. This study opened up a new horizon for exploring the novel properties of phytase for other applications.

Changes in broiler breeder hen's immunity by zinc oxide and phytase

BACKGROUND

The immune response of aged broiler breeder hens is influenced by many factors including obesity and aged lymphatic organs, but may improve by increasing the bioavailability of various nutrients such as zinc (Zn). Dietary supplementation of phytase can improve Zn availability in senescent broiler breeder hens.

AIMS

The aim of this study was to investigate the effect of supplementary zinc oxide (ZnO) and phytase in a maize-soybean meal-based diet on immune responses of broiler breeder hens.

METHODS

In a 2 × 4 factorial arrangement, a total of 128 hens were randomly assigned into eight groups. The birds received two levels of phytase (0 or 300 U/kg diet) and four levels of ZnO (30, 60, 90, and 120 mg/kg diet) for 13 successive wk (59-72 wk of age).

RESULTS

Results showed that phytase supplementation significantly increased immunoglobulin M (IgM), cutaneous basophil hypersensitivity (CBH) responses, total number of leukocytes, percentage of lymphocytes, and heterophil to lymphocyte ratios. The percentage of basophils and monocytes, however, decreased with phytase supplementation. Supplementation of ZnO increased anti-sheep red blood cells (SRBC) antibody titer, IgM, CBH responses, the total number of leukocytes, and the percentage of lymphocytes. Dietary supplementation of ZnO decreased the percentage of heterophil, and heterophil to lymphocyte ratio. A significant interaction effect of phytase and ZnO was found on the total number of leukocytes and percentage of lymphocytes.

CONCLUSION

Dietary supplementation of ZnO (90 mg/kg diet) and phytase had some positive effects on improving immune responses in broiler breeder hens.

Expression and Biochemical Characterization of a Yersinia intermedia Phytase Expressed in Escherichia coli

BACKGROUND

Phytases are enzymes capable of degrading phytic acid and used in animal feed supplementation in order to improve digestibility through the release of minerals such as phosphorus.

OBJECTIVE

The main goal of this study was to express and characterize a Yersinia intermedia phytase expressed in Escherichia coli cells.

METHODS

The Y. intermedia phytase gene was synthesized and overexpressed in Escherichia coli cells. The phytase recombinante (rPHY) was purified to homogeneity using a Ni-NTA column. The biochemical and biophysical properties of the rPHY were measured in order to fully characterize the recombinant enzyme. The following patents database were consulted: Espacenet, USPTO, LATIPAT, Patent Scope, WIPO and Google Patents.

RESULTS

The results showed that the rPHY is active at 37-40ºC and presented an optimal pH and temperature of 8.0 and 40°C, respectively. The phytase rPHY was activated by Cu2+ ion and showed resistance to trypsin and pepsin, retaining 55% of the activity at the ratio of 0.02. Furthermore, the dissociation constant (Kd = 1.1150 ± 0.0087 mM), as estimated by a fluorescence binding assay, suggests a medium affinity of the enzyme with the substrate.

CONCLUSION

The results of this article can be considered as innovative and for this reason, they were protected by Intellectual Property Law in Brazil. Take together, the biochemical properties of the rPHY could be useful in future for its industrial application of this enzyme as an additive in the monogastric feed.

Display of Escherichia coli Phytase on the Surface of Bacillus subtilis Spore Using CotG as an Anchor Protein

Escherichia coli phytase (AppA) has been widely used as an exogenous feed enzyme for monogastric animals; however, the production of this enzyme has been examined primarily in E. coli and yeast expression systems. As an alternative to production of soluble phytase, an enzyme immobilization method using the Bacillus subtilis spore outer-coat protein CotG as an anchoring motif for the display of the AppA was attempted. Using this motif, AppA was successfully produced on the spore surface of B. subtilis as verified by Western blot analysis and phytase activity measurements. Analysis of the pH stability indicated that more than 50% activity was retained after incubation at four different pH values (2.0, 4.0, 7.0, and 8.0) for up to 12 h, with maximum activity observed at pH 4.5. The highest enzyme activity seen at 55 °C and thermal stability measurements demonstrated that more than 30% activity remained after 30 min incubation at 60 °C. The spore surface-displayed AppA was resistant to pepsin, and more stable than phytase produced previously using a yeast expression system. Furthermore, we present data indicating that the use of peptide linkers may help improve the bioactivity of displayed enzymes on the spore surface of B. subtilis.

Comparative evaluation of fermented and non-fermented de-oiled rice bran with or without exogenous enzymes supplementation in the diet of Labeo rohita (Hamilton, 1822)

A 60-day feeding trial was conducted to study the effect of exogenous enzymes (xylanase and phytase) supplementation in the non-fermented and fermented de-oiled rice bran (DORB)-based diet of Labeo rohita. Four test diets (T1-DORB-based diet, T2-fermented DORB-based diet, T3-phytase and xylanase supplemented DORB-based diet, and T4-phytase and xylanase supplemented fermented DORB-based diet) were formulated and fed to the respective groups. Test diets T3 and T4 were supplemented with 0.01% xylanase (16,000 U kg^-1) and 0.01% phytase (500 U kg^-1) enzymes. One hundred twenty juveniles of L. rohita, with an average weight 5.01 ± 0.02 g, were stocked in 12 uniform size plastic rectangular tanks in triplicate with 10 fishes per tank following a completely randomized design (CRD). Exogenous enzyme supplementation to the T3 group significantly improved the growth performance of L. rohita (p < 0.05). Fermented DORB fed groups registered significantly lower growth irrespective of the supplementation of exogenous enzymes. The carcass composition (except CP %), enzyme activities (except amylase activity), globulin, and A/G ratio did not vary significantly (p > 0.05). Based on the results of the present study, it is concluded that exogenous enzyme supplementation significantly increases the growth of fish fed with DORB-based diet.

Enhancing thermal tolerance of Aspergillus niger PhyA phytase directed by structural comparison and computational simulation

Background

Phytase supplied in feeds for monogastric animals is important for improving nutrient uptake and reducing phosphorous pollution. High-thermostability phytases are particularly desirable due to their ability to withstand transient high temperatures during feed pelleting procedures. A comparison of crystal structures of the widely used industrial Aspergillus niger PhyA phytase (AnP) with its close homolog, the thermostable Aspergillus fumigatus phytase (AfP), suggests 18 residues in three segments associated with thermostability. In this work, we aim to improve the thermostability of AnP through site-directed mutagenesis. We identified favorable mutations based on structural comparison of homologous phytases and molecular dynamics simulations.

Results

A recombinant phytase (AnP-M1) was created by substituting 18 residues in AnP with their AfP analogs. AnP-M1 exhibited greater thermostability than AnP at 70 °C. Molecular dynamics simulations suggested newly formed hydrogen bonding interactions with nine substituted residues give rise to the improved themostability. Thus, another recombinant phytase (AnP-M2) with just these nine point substitutions was created. AnP-M2 demonstrated superior thermostability among all AnPs at ≥70 °C: AnP-M2 maintained 56% of the maximal activity after incubation at 80 °C for 1 h; AnP-M2 retained 30-percentage points greater residual activity than that of AnP and AnP-M1 after 1 h incubation at 90 °C.

Conclusions

The resulting AnP-M2 is an attractive candidate in industrial applications, and the nine substitutions in AnP-M2 are advantageous for phytase thermostability. This work demonstrates that a strategy combining structural comparison of homologous enzymes and computational simulation to focus on important interactions is an effective method for obtaining a thermostable enzyme.

Electronic supplementary material

The online version of this article (10.1186/s12896-018-0445-y) contains supplementary material, which is available to authorized users.

Microbial degradation of myo-inositol hexakisphosphate (IP6): specificity, kinetics, and simulation

Microbial degradation of myo-inositol hexakisphosphate (IP6) is crucial to deal with nutritional problems in monogastric animals as well as to prevent environmental phosphate pollution. The present study deals with the degradation of IP6 by microorganisms such as Sporosarcina spp. pasteurii, globiospora, psychrophila, Streptococcus thermophilus and Saccharomyces boulardii. These microbes were screened for phytase production under laboratory conditions. The specificity of the enzyme was tested for various phosphorylated substrates such as sodium phytate (IP6), sodium hexametaphosphate, phenyl phosphate, α-d-glucose-6 phosphate, inosine 5' monophosphate and pyridoxal 5' phosphate. These enzymes were highly specific to IP6. The influence of modulators such as phytochemicals and metal ions on the enzymatic activity was assessed. These modulators in different concentrations had varying effect on microbial phytases. Calcium (in optimal concentration of 0.5 M) played an important role in enzyme activation. The enzymes were then characterized based on their molecular weight 41~43 kDa. The phytase-producing microbes were assessed for IP6 degradation in a simulated intestinal setup. Among the selected microbes, Sporosarcina globiospora hydrolyzed IP6 effectively, as confirmed by colorimetric time-based analysis.

Phytase-Producing Potential and Other Functional Attributes of Lactic Acid Bacteria Isolates for Prospective Probiotic Applications

Wide variations among multifaceted-health benefitting attributes of probiotics fueled investigations on targeting efficacious probiotics. In the current study, lactic acid bacteria (LAB) isolated from poultry gut, feces of rat, chicken, human infants, and fermented foods were characterized for desired probiotic functional properties including the phytase-producing ability which is one of the wanted characteristics for probiotics for potential applications for upgrading animal nutrition, enhancing feed conversion, and minimizing anti-nutritional properties. Among 62 LAB isolates Weissella kimchii R-3 an isolate from poultry gut exhibited substantial phytase-producing ability (1.77 U/ml) in addition to other functional probiotic characteristics viz. hydrophobicity, autoaggregation, coaggregation with bacterial pathogens, and antimicrobial activity against pathogens. Survival of W. kimchii R-3 cells (in free and calcium alginate encapsulated state) was examined sequentially in simulated gastric and intestinal juices. Encapsulated cells exhibited better survival under simulated gut conditions indicating that encapsulation conferred considerable protection against adverse gut conditions. Furthermore, simulated gastric and intestinal juices with pepsin and pancreatin showed higher survival of cells than the juices without pepsin and pancreatin. W. kimchii R-3 due to its significant functional probiotic attributes may have prospective for commercial applications in human/animal nutrition.

Improved microscale cultivation of Pichia pastoris for clonal screening

Background

Expanding the application of technical enzymes, e.g., in industry and agriculture, commands the acceleration and cost-reduction of bioprocess development. Microplates and shake flasks are massively employed during screenings and early phases of bioprocess development, although major drawbacks such as low oxygen transfer rates are well documented. In recent years, miniaturization and parallelization of stirred and shaken bioreactor concepts have led to the development of novel microbioreactor concepts. They combine high cultivation throughput with reproducibility and scalability, and represent promising tools for bioprocess development.

Results

Parallelized microplate cultivation of the eukaryotic protein production host Pichia pastoris was applied effectively to support miniaturized phenotyping of clonal libraries in batch as well as fed-batch mode. By tailoring a chemically defined growth medium, we show that growth conditions are scalable from microliter to 0.8 L lab-scale bioreactor batch cultivation with different carbon sources. Thus, the set-up allows for a rapid physiological comparison and preselection of promising clones based on online data and simple offline analytics. This is exemplified by screening a clonal library of P. pastoris constitutively expressing AppA phytase from Escherichia coli. The protocol was further modified to establish carbon-limited conditions by employing enzymatic substrate-release to achieve screening conditions relevant for later protein production processes in fed-batch mode.

Conclusion

The comparison of clonal rankings under batch and fed-batch-like conditions emphasizes the necessity to perform screenings under process-relevant conditions. Increased biomass and product concentrations achieved after fed-batch microscale cultivation facilitates the selection of top producers. By reducing the demand to conduct laborious and cost-intensive lab-scale bioreactor cultivations during process development, this study will contribute to an accelerated development of protein production processes.

Electronic supplementary material

The online version of this article (10.1186/s40694-018-0053-6) contains supplementary material, which is available to authorized users.

Molecular modeling and docking of recombinant HAP-phytase of a thermophilic mould Sporotrichum thermophile reveals insights into molecular catalysis and biochemical properties

A thermostable and protease-resistant HAP-phytase of Sporotrichum thermophile was over-expressed in Pichia pastoris X-33. Purified recombinant phytase displayed all its biochemical properties similar to wild type. Molecular modeling and docking of phytase with various substrates showed differential binding patterns with GoldScore values ranging from 40.61 to 79.78. Docking with different substrates revealed strong binding affinity with ATP and phytic acid, while the lowest with AMP and phosphoenol pyruvate. This was further confirmed using biochemical assays, as the recombinant enzyme displayed broad substrate specificity. Docking with inhibitors also showed differential binding with GoldScore values ranging from 22.94 (2,3-butanedione) to 85.72 (myo-inositol hexasulphate). Validation using biochemical analysis revealed that both 2,3-butanedione and phenyl glyoxal inhibited the phytase activity significantly. Furthermore, presence of inorganic phosphate in the reaction mixture also inhibited the phytase activity, as there was no activity at and beyond 0.8 mM. Docking of phytase with metavanadate showed binding at the same atom in the active-site where the substrate i.e. phytic acid binds. Vanadium incorporation resulted in the catalytic conversion of phytase into a peroxidase with concomitant inhibition of phytase activity. Peroxidase activity was high in acidic range and the product formation showed correlation with reaction time. Furthermore, molecular modeling and docking of recombinant HAP-phytase of a thermophilic mould S. thermophile reveals insights into molecular catalysis that is validated by the biochemical properties.

Extracellular Secretion of Phytase from Transgenic Wheat Roots Allows Utilization of Phytate for Enhanced Phosphorus Uptake

A significant portion of organic phosphorus comprises of phytates which are not available to wheat for uptake. Hence for enabling wheat to utilize organic phosphorus in form of phytate, transgenic wheat expressing phytase from Aspergillus japonicus under barley root-specific promoter was developed. Transgenic events were initially screened via selection media containing BASTA, followed by PCR and BASTA leaf paint assay after hardening. Out of 138 successfully regenerated T_o events, only 12 had complete constructs and thus further analyzed. Positive T1 transgenic plants, grown in sand, exhibited 0.08-1.77, 0.02-0.67 and 0.44-2.14 fold increase in phytase activity in root extracts, intact roots and external root solution, respectively, after 4 weeks of phosphorus stress. Based on these results, T2 generation of four best transgenic events was further analyzed which showed up to 1.32, 56.89, and 15.40 fold increase in phytase activity in root extracts, intact roots and external root solution, respectively, while in case of real-time PCR, maximum fold increase of 19.8 in gene expression was observed. Transgenic lines showed 0.01-1.18 fold increase in phosphorus efficiency along with higher phosphorus content when supplied phytate or inorganic phosphorus than control plants. Thus, this transgenic wheat may aid in reducing fertilizer utilization and enhancing wheat yield.

Do not neglect calcium: a systematic review and meta-analysis (meta-regression) of its digestibility and utilisation in growing and finishing pigs

Ca digestibility and utilisation in growing pigs are not well understood, and are usually neglected in diet formulation. This has implications not only for the accurate determination of its requirements but also for its interactions with other nutrients. A systematic review and meta-analysis (meta-regression) of published trials was carried out to quantify factors affecting Ca absorption and utilisation, and to derive an estimate of Ca endogenous excretion. The analysis was carried out on the data from forty studies, corresponding to 201 treatments performed on 1204 pigs. The results indicated that although Ca absorption and retention (g/kg of body weight per d) increased with increasing Ca intake (P<0·001), non-phytate-P intake (P<0·001) and exogenous phytase supplementation (P<0·001), these values decreased with increasing phytate-P intake (P<0·05). Interactions between exogenous phytase and Ca intake, indicating reduced efficacy of this enzyme (P<0·001), and between phytate-P intake and exogenous phytase, counteracting the direct negative effect of phytate-P (P<0·05) on Ca absorption and retention, were also detected. There were no effects of animal-related characteristics, such as pig genotype in Ca absorption and retention. The large amount of variance explained in Ca absorption (90 %) and retention (91 %) supported our choice of independent variables. Endogenous Ca losses obtained via linear regression were 239 mg/kg of DM intake (95 % CI 114, 364). These outcomes advance the current understanding of Ca digestibility and utilisation, and should contribute towards establishing requirements for digestible Ca. Consequently, pig diets will be more correctly formulated if digestible Ca values are used in estimating requirements for Ca.

Effect of Dietary Phytase Supplementation on Bone and Hyaline Cartilage Development of Broilers Fed with Organically Complexed Copper in a Cu-Deficient Diet

Tibial mechanical, chemical, and histomorphometrical traits were investigated for growing male Ross 308 broiler chickens fed diets that had copper (Cu) from organic source at a lowered level of 25% of the daily requirement (4 mg kg-1 of a premix) with or without phytase. Dietary treatments were control non-copper, non-phytase group (0 Suppl); 4 mg kg-1 Cu non-phytase group (25%Cu); and 4 mg kg-1 Cu + 500 FTU kg-1 phytase group (25%Cu + phyt). The results show that birds fed with the addition of phytase exhibited improved weight gain and final body weight and had increased serum IGF-1 and osteocalcin concentrations. The serum concentration of Cu and P did not differ between groups; however, Ca concentration decreased in the 25%Cu + phyt group when compared to the 25%Cu group. Added Cu increased bone Ca, P, Cu, and ash content in Cu-supplemented groups, but bone weight and length increased only by the addition of phytase. Bone geometry, yield, and ultimate strengths were affected by Cu and phytase addition. A decrease of the elastic stress and ultimate stress of the tibia in Cu-supplemented groups was observed. The histomorphometric analysis showed a positive effect of Cu supplementation on real bone volume and trabecular thickness in the tibia metaphyseal trabeculae; additionally, phytase increased the trabeculea number. The supplementation with Cu significantly increased the total articular cartilage and growth plate cartilage thickness; however, the changes in thickness of particular zones were dependent upon phytase addition. In summary, dietary Cu supplements given to growing broilers with Cu in their diet restricted to 25% of the daily requirement had a positive effect on bone metabolism, and phytase supplementation additionally improved cartilage development.

Oxygen uptake rate as a tool for on-line estimation of cell biomass and bed temperature in a novel solid-state fermentation bioreactor

Direct measurement of cell biomass is difficult in a solid-state fermentation (SSF) process involving filamentous fungi since the mycelium and the solid substrate are often inseparable. However, respiratory data are rich in information for real-time monitoring of microbial biomass production. In this regard, a correlation was obtained between oxygen uptake rate (OUR) and biomass concentration (X) of Rhizopus oryzae MTCC 1987, during phytase production, in an intermittently mixed novel SSF bioreactor. To obtain the correlation, various models describing sigmoidal growth were tested, namely the logistic, Gompertz, Stannard, and Schnute models. Regression analysis of experimental results, at different operating conditions of inlet air flow rate and relative humidity suggested that OUR and X were correlated well by the logistic model (R² > 0.90). To corroborate the use of respiratory data for on-line measurement of metabolic activity, OUR was related to metabolic heat generation rate (R_q), and the logistic model was found to satisfactorily correlate R_q and X as well. The model parameter, Y_Q/X, when substituted into a heat transfer design equation, along with the values of other parameters and operating variables, gave reliable estimates of bed temperature. The correlations developed in the present study, between respiratory activity and biomass concentration may be extended on to other SSF processes for further validation and real-time monitoring of cell biomass and bed temperature.

Effect of enzymatic treatment on phytate content and mineral bioacessability in soy drink

The objective of this study was to evaluate in vitro bioaccessibility of calcium (Ca), iron (Fe) and zinc (Zn) in soy drink after phytase treatment and correlate it with the content of myo-inositol phosphates. Samples of commercial soy drink products and one sample produced in the laboratory by maceration were evaluated. Phytase was applied using 300 U per liter in 60 min considering the phosphate release. The content of myo-inositol tris-, tetrakis-, pentakis and hexakisphosphate was not observed after phytase treatment. The solubility assay showed an increase from 2.0% to 20.8% for Ca, 2.2% to 37.1% for Fe and 38.8% to 67.4% for Zn after phytase treatment with significant differences (p ≤ 0.05) for most samples. Dialysis assay demonstrated 1.0% to 9.5% for Ca after phytase treatment (p ≤ 0.05) except for one commercial sample. The phytase treatment is a valuable alternative process for improving mineral natural availability in soy drink and decreased the use of salts in the fortification.

Production of extracellular heterologous proteins in Streptomyces rimosus, producer of the antibiotic oxytetracycline

Among the Streptomyces species, Streptomyces lividans has often been used for the production of heterologous proteins as it can secrete target proteins directly into the culture medium. Streptomyces rimosus, on the other hand, has for long been used at an industrial scale for oxytetracycline production, and it holds 'Generally Recognised As Safe' status. There are a number of properties of S. rimosus that make this industrial strain an attractive candidate as a host for heterologous protein production, including (1) rapid growth rate; (2) growth as short fragments, as for Escherichia coli; (3) high efficiency of transformation by electroporation; and (4) secretion of proteins into the culture medium. In this study, we specifically focused our efforts on an exploration of the use of the Sec secretory pathway to export heterologous proteins in a S. rimosus host. We aimed to develop a genetic tool kit for S. rimosus and to evaluate the extracellular production of target heterologous proteins of this industrial host. This study demonstrates that S. rimosus can produce the industrially important enzyme phytase AppA extracellularly, and analogous to E. coli as a host, application of His-Tag/Ni-affinity chromatography provides a simple and rapid approach to purify active phytase AppA in S. rimosus. We thus demonstrate that S. rimosus can be used as a potential alternative protein expression system.

Purification and biochemical characterization of an Aspergillus niger phytase produced by solid-state fermentation using triticale residues as substrate

In this study, an extracellular phytase produced by Aspergillus niger 7A-1, was biochemically characterized for possible industrial application. The enzyme was purified from a crude extract obtained by solid-state fermentation (SSF) of triticale waste. The extract was obtained by microfiltration, ultrafiltration (300, 100 and 30 kDa) and DEAE-Sepharose column chromatography. The molecular weight of the purified enzyme was estimated to be 89 kDa by SDS-PAGE. The purified enzyme was most active at pH 5.3 and 56 °C, and retained 50% activity over a wide pH range of 4 to 7. The enzymatic thermostability assay showed that the enzyme retained more than 70% activity at 80 °C for 60 s, 40% activity for 120 s and 9% after 300 s. The phytase showed broad substrate specificity, a K_m value of 220 μM and V_max of 25 μM/min. The purified phytase retained 50% of its activity with phosphorylated compounds such as phenyl phosphate, 1-Naphthyl phosphate, 2-Naphthyl phosphate, p-Nitrophenyl phosphate and Glycerol-2-phosphate. The inhibition of phytase activity by metal ions was observed to be drastically inhibited (50%) by Ca⁺⁺ and was slightly inhibited (10%) by Ni⁺⁺, K⁺, and Na⁺, at 10 and 20 mM concentrations. A positive effect was obtained with Mg⁺⁺, Mn⁺⁺, Cu⁺⁺, Cd⁺⁺ and Ba⁺⁺ at 25 and 35% with stimulatory effect on the phytase activity.

Microbial phytase: Impact of advances in genetic engineering in revolutionizing its properties and applications

Phytases are enzymes that increase the availability of phosphorous in monogastric diet and reduces the anti-nutrition effect of phytate. This review highlights contributions of recombinant technology to phytase research during the last decade with specific emphasis on new generation phytases. Application of modern molecular tools and genetic engineering have aided the discovery of novel phytase genes, facilitated its commercial production and expanded its applications. In future, by adopting most recent gene improvement techniques, more efficient next generation phytases can be developed for specific applications.

Time-series responses of swine plasma metabolites to ingestion of diets containing myo-inositol or phytase

The effect of the ingestion of diets containing either myo-inositol or exogenous phytase on plasma metabolites was examined using 29 kg barrows. The diets were: control (maize, soya, rapeseed, rice bran), control plus 2 g/kg myo-inositol, control plus 1000 phytase units (FYT)/kg or 3000 FYT/kg exogenous phytase. Pigs were housed in a PigTurn device and blood was collected, from jugular catheters, via an automated system at -30, (30 min before feeding), 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300 and 360 min post-feeding. The addition of 2 g/kg myo-inositol to the basal diet resulted in an increase in plasma myo-inositol concentration that was evident 45-60 min after diet introduction and persisted to 360 min post-feeding. Similarly, supplementation of the basal diet with either 1000 or 3000 FYT/kg exogenous phytase resulted in an increase in plasma myo-inositol concentration that was still rising 360 min post-feeding. Plasma P concentration was increased over time by the addition of 1000 and 3000 FYT/kg phytase, but not by the addition of myo-inositol. Other plasma metabolites examined were not affected by dietary treatment. It can be concluded that oral delivery of myo-inositol results in rapid increase in plasma myo-inositol concentrations that peak approximately 45-60 min after feeding. Use of supplemental phytase achieves similar increases in myo-inositol concentration in plasma but the appearance is more gradual. Furthermore, supplementation of pig diets with exogenous phytase results in rapid appearance of P in plasma that may be sustained over time relative to diets with no added phytase.

Phytase production by Aspergillus niger NCIM 563 for a novel application to degrade organophosphorus pesticides

The production of phytase using Aspergillus niger NCIM 563 under submerged fermentation conditions was studied using protein rich chickpea flour as substrate. Employing a hybrid statistical media optimization strategy of Plackett-Burman and Box-Behnken experimental designs in shake-flasks gave an increased phytase activity from an initial 66 IU/mL in 216 h to 160 IU/mL in a reduced time of 132 h. Productivity, thus increased by 3.97 times from 7.3 to 29 IU/mL/day. Using the optimized media, the production was successfully scaled-up further and improved up to 164 IU/mL in 96 h by studies carried out employing 2 and 10-L fermenters. The enzyme supernatant was recovered using centrifugal separation of biomass and the stability of the produced phytase was tested for animal feed applications under gastric conditions. In vitro degradation studies of water soluble monocrotophos, methyl parathion and water insoluble chlorpyrifos, pesticides used extensively in agriculture was carried out. It was observed by HPLC analysis that phytase could degrade 72% of chlorpyrifos at pH 7.0, 35 °C. Comparable results were obtained with monocrotophos and methyl parathion. With chlorpyrifos at higher temperature 50 °C as much as 91% degradation could be obtained. The degradation of chlorpyrifos was further validated by spraying phytase on harvested green chilli (Capsicum annuum L) under normal conditions of pH 7.0, 35 °C and the degradation products obtained analyzed by LCMS. Thus, the present study brings out a potentially novel application of phytase for biodegradation of organophosphorus pesticides.